diff --git a/news/11457.removal.rst b/news/11457.removal.rst
new file mode 100644
index 00000000000..eb579147eeb
--- /dev/null
+++ b/news/11457.removal.rst
@@ -0,0 +1,2 @@
+Remove support for the legacy setup.py develop editable method in setuptools
+editable installs; setuptools >= 64 is now required.
diff --git a/news/11859.removal.rst b/news/11859.removal.rst
new file mode 100644
index 00000000000..fa56c8d05f6
--- /dev/null
+++ b/news/11859.removal.rst
@@ -0,0 +1,2 @@
+Remove the deprecated ``--global-option`` and ``--build-option``.
+``--config-setting`` is now the only way to pass options to the build backend.
diff --git a/news/6334.removal.rst b/news/6334.removal.rst
new file mode 100644
index 00000000000..791846540b2
--- /dev/null
+++ b/news/6334.removal.rst
@@ -0,0 +1,2 @@
+Remove support for the deprecated ``setup.py bdist_wheel`` mechanism. Consequently,
+``--use-pep517`` is now always on, and ``--no-use-pep517`` has been removed.
diff --git a/src/pip/_internal/cli/cmdoptions.py b/src/pip/_internal/cli/cmdoptions.py
index 3519dadf13d..5b47c65013f 100644
--- a/src/pip/_internal/cli/cmdoptions.py
+++ b/src/pip/_internal/cli/cmdoptions.py
@@ -11,7 +11,6 @@
 # mypy: strict-optional=False
 from __future__ import annotations
 
-import importlib.util
 import logging
 import os
 import pathlib
@@ -161,8 +160,7 @@ class PipOption(Option):
     action="store_true",
     default=False,
     help=(
-        "Allow pip to only run in a virtual environment; "
-        "exit with an error otherwise."
+        "Allow pip to only run in a virtual environment; exit with an error otherwise."
     ),
 )
 
@@ -813,62 +811,16 @@ def _handle_dependency_group(
     dest="check_build_deps",
     action="store_true",
     default=False,
-    help="Check the build dependencies when PEP517 is used.",
+    help="Check the build dependencies.",
 )
 
 
-def _handle_no_use_pep517(
-    option: Option, opt: str, value: str, parser: OptionParser
-) -> None:
-    """
-    Process a value provided for the --no-use-pep517 option.
-
-    This is an optparse.Option callback for the no_use_pep517 option.
-    """
-    # Since --no-use-pep517 doesn't accept arguments, the value argument
-    # will be None if --no-use-pep517 is passed via the command-line.
-    # However, the value can be non-None if the option is triggered e.g.
-    # by an environment variable, for example "PIP_NO_USE_PEP517=true".
-    if value is not None:
-        msg = """A value was passed for --no-use-pep517,
-        probably using either the PIP_NO_USE_PEP517 environment variable
-        or the "no-use-pep517" config file option. Use an appropriate value
-        of the PIP_USE_PEP517 environment variable or the "use-pep517"
-        config file option instead.
-        """
-        raise_option_error(parser, option=option, msg=msg)
-
-    # If user doesn't wish to use pep517, we check if setuptools is installed
-    # and raise error if it is not.
-    packages = ("setuptools",)
-    if not all(importlib.util.find_spec(package) for package in packages):
-        msg = (
-            f"It is not possible to use --no-use-pep517 "
-            f"without {' and '.join(packages)} installed."
-        )
-        raise_option_error(parser, option=option, msg=msg)
-
-    # Otherwise, --no-use-pep517 was passed via the command-line.
-    parser.values.use_pep517 = False
-
-
 use_pep517: Any = partial(
     Option,
     "--use-pep517",
     dest="use_pep517",
     action="store_true",
-    default=None,
-    help="Use PEP 517 for building source distributions "
-    "(use --no-use-pep517 to force legacy behaviour).",
-)
-
-no_use_pep517: Any = partial(
-    Option,
-    "--no-use-pep517",
-    dest="use_pep517",
-    action="callback",
-    callback=_handle_no_use_pep517,
-    default=None,
+    default=True,
     help=SUPPRESS_HELP,
 )
 
@@ -901,30 +853,11 @@ def _handle_config_settings(
     action="callback",
     callback=_handle_config_settings,
     metavar="settings",
-    help="Configuration settings to be passed to the PEP 517 build backend. "
+    help="Configuration settings to be passed to the build backend. "
     "Settings take the form KEY=VALUE. Use multiple --config-settings options "
     "to pass multiple keys to the backend.",
 )
 
-build_options: Callable[..., Option] = partial(
-    Option,
-    "--build-option",
-    dest="build_options",
-    metavar="options",
-    action="append",
-    help="Extra arguments to be supplied to 'setup.py bdist_wheel'.",
-)
-
-global_options: Callable[..., Option] = partial(
-    Option,
-    "--global-option",
-    dest="global_options",
-    action="append",
-    metavar="options",
-    help="Extra global options to be supplied to the setup.py "
-    "call before the install or bdist_wheel command.",
-)
-
 no_clean: Callable[..., Option] = partial(
     Option,
     "--no-clean",
diff --git a/src/pip/_internal/cli/req_command.py b/src/pip/_internal/cli/req_command.py
index dc1328ff019..5a7e28aa3a1 100644
--- a/src/pip/_internal/cli/req_command.py
+++ b/src/pip/_internal/cli/req_command.py
@@ -163,7 +163,6 @@ def make_resolver(
         ignore_requires_python: bool = False,
         force_reinstall: bool = False,
         upgrade_strategy: str = "to-satisfy-only",
-        use_pep517: bool | None = None,
         py_version_info: tuple[int, ...] | None = None,
     ) -> BaseResolver:
         """
@@ -172,7 +171,6 @@ def make_resolver(
         make_install_req = partial(
             install_req_from_req_string,
             isolated=options.isolated_mode,
-            use_pep517=use_pep517,
         )
         resolver_variant = cls.determine_resolver_variant(options)
         # The long import name and duplicated invocation is needed to convince
@@ -241,7 +239,6 @@ def get_requirements(
                 req,
                 comes_from=None,
                 isolated=options.isolated_mode,
-                use_pep517=options.use_pep517,
                 user_supplied=True,
                 config_settings=getattr(options, "config_settings", None),
             )
@@ -252,7 +249,6 @@ def get_requirements(
                 req_to_add = install_req_from_req_string(
                     req,
                     isolated=options.isolated_mode,
-                    use_pep517=options.use_pep517,
                     user_supplied=True,
                 )
                 requirements.append(req_to_add)
@@ -262,7 +258,6 @@ def get_requirements(
                 req,
                 user_supplied=True,
                 isolated=options.isolated_mode,
-                use_pep517=options.use_pep517,
                 config_settings=getattr(options, "config_settings", None),
             )
             requirements.append(req_to_add)
@@ -275,7 +270,6 @@ def get_requirements(
                 req_to_add = install_req_from_parsed_requirement(
                     parsed_req,
                     isolated=options.isolated_mode,
-                    use_pep517=options.use_pep517,
                     user_supplied=True,
                     config_settings=(
                         parsed_req.options.get("config_settings")
diff --git a/src/pip/_internal/commands/download.py b/src/pip/_internal/commands/download.py
index 900fb403d6f..6ab6b2017f9 100644
--- a/src/pip/_internal/commands/download.py
+++ b/src/pip/_internal/commands/download.py
@@ -7,7 +7,6 @@
 from pip._internal.cli.req_command import RequirementCommand, with_cleanup
 from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.operations.build.build_tracker import get_build_tracker
-from pip._internal.req.req_install import check_legacy_setup_py_options
 from pip._internal.utils.misc import ensure_dir, normalize_path, write_output
 from pip._internal.utils.temp_dir import TempDirectory
 
@@ -38,7 +37,6 @@ def add_options(self) -> None:
         self.cmd_opts.add_option(cmdoptions.constraints())
         self.cmd_opts.add_option(cmdoptions.requirements())
         self.cmd_opts.add_option(cmdoptions.no_deps())
-        self.cmd_opts.add_option(cmdoptions.global_options())
         self.cmd_opts.add_option(cmdoptions.no_binary())
         self.cmd_opts.add_option(cmdoptions.only_binary())
         self.cmd_opts.add_option(cmdoptions.prefer_binary())
@@ -48,7 +46,6 @@ def add_options(self) -> None:
         self.cmd_opts.add_option(cmdoptions.progress_bar())
         self.cmd_opts.add_option(cmdoptions.no_build_isolation())
         self.cmd_opts.add_option(cmdoptions.use_pep517())
-        self.cmd_opts.add_option(cmdoptions.no_use_pep517())
         self.cmd_opts.add_option(cmdoptions.check_build_deps())
         self.cmd_opts.add_option(cmdoptions.ignore_requires_python())
 
@@ -104,7 +101,6 @@ def run(self, options: Values, args: list[str]) -> int:
         )
 
         reqs = self.get_requirements(args, options, finder, session)
-        check_legacy_setup_py_options(options, reqs)
 
         preparer = self.make_requirement_preparer(
             temp_build_dir=directory,
@@ -122,7 +118,6 @@ def run(self, options: Values, args: list[str]) -> int:
             finder=finder,
             options=options,
             ignore_requires_python=options.ignore_requires_python,
-            use_pep517=options.use_pep517,
             py_version_info=options.python_version,
         )
 
diff --git a/src/pip/_internal/commands/install.py b/src/pip/_internal/commands/install.py
index 1ef7a0f4410..d9e67637c52 100644
--- a/src/pip/_internal/commands/install.py
+++ b/src/pip/_internal/commands/install.py
@@ -41,7 +41,6 @@
 from pip._internal.req import install_given_reqs
 from pip._internal.req.req_install import (
     InstallRequirement,
-    check_legacy_setup_py_options,
 )
 from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.filesystem import test_writable_dir
@@ -59,7 +58,7 @@
     running_under_virtualenv,
     virtualenv_no_global,
 )
-from pip._internal.wheel_builder import build, should_build_for_install_command
+from pip._internal.wheel_builder import build
 
 logger = getLogger(__name__)
 
@@ -210,12 +209,10 @@ def add_options(self) -> None:
         self.cmd_opts.add_option(cmdoptions.ignore_requires_python())
         self.cmd_opts.add_option(cmdoptions.no_build_isolation())
         self.cmd_opts.add_option(cmdoptions.use_pep517())
-        self.cmd_opts.add_option(cmdoptions.no_use_pep517())
         self.cmd_opts.add_option(cmdoptions.check_build_deps())
         self.cmd_opts.add_option(cmdoptions.override_externally_managed())
 
         self.cmd_opts.add_option(cmdoptions.config_settings())
-        self.cmd_opts.add_option(cmdoptions.global_options())
 
         self.cmd_opts.add_option(
             "--compile",
@@ -334,8 +331,6 @@ def run(self, options: Values, args: list[str]) -> int:
             target_temp_dir_path = target_temp_dir.path
             self.enter_context(target_temp_dir)
 
-        global_options = options.global_options or []
-
         session = self.get_default_session(options)
 
         target_python = make_target_python(options)
@@ -355,7 +350,6 @@ def run(self, options: Values, args: list[str]) -> int:
 
         try:
             reqs = self.get_requirements(args, options, finder, session)
-            check_legacy_setup_py_options(options, reqs)
 
             wheel_cache = WheelCache(options.cache_dir)
 
@@ -384,7 +378,6 @@ def run(self, options: Values, args: list[str]) -> int:
                 ignore_requires_python=options.ignore_requires_python,
                 force_reinstall=options.force_reinstall,
                 upgrade_strategy=upgrade_strategy,
-                use_pep517=options.use_pep517,
                 py_version_info=options.python_version,
             )
 
@@ -425,17 +418,13 @@ def run(self, options: Values, args: list[str]) -> int:
             protect_pip_from_modification_on_windows(modifying_pip=modifying_pip)
 
             reqs_to_build = [
-                r
-                for r in requirement_set.requirements_to_install
-                if should_build_for_install_command(r)
+                r for r in requirement_set.requirements_to_install if not r.is_wheel
             ]
 
             _, build_failures = build(
                 reqs_to_build,
                 wheel_cache=wheel_cache,
                 verify=True,
-                build_options=[],
-                global_options=global_options,
             )
 
             if build_failures:
@@ -459,7 +448,6 @@ def run(self, options: Values, args: list[str]) -> int:
 
             installed = install_given_reqs(
                 to_install,
-                global_options,
                 root=options.root_path,
                 home=target_temp_dir_path,
                 prefix=options.prefix_path,
diff --git a/src/pip/_internal/commands/lock.py b/src/pip/_internal/commands/lock.py
index e4a978d5aaa..cd825ec19ce 100644
--- a/src/pip/_internal/commands/lock.py
+++ b/src/pip/_internal/commands/lock.py
@@ -11,9 +11,6 @@
 from pip._internal.cli.status_codes import SUCCESS
 from pip._internal.models.pylock import Pylock, is_valid_pylock_file_name
 from pip._internal.operations.build.build_tracker import get_build_tracker
-from pip._internal.req.req_install import (
-    check_legacy_setup_py_options,
-)
 from pip._internal.utils.logging import getLogger
 from pip._internal.utils.misc import (
     get_pip_version,
@@ -69,7 +66,6 @@ def add_options(self) -> None:
         self.cmd_opts.add_option(cmdoptions.ignore_requires_python())
         self.cmd_opts.add_option(cmdoptions.no_build_isolation())
         self.cmd_opts.add_option(cmdoptions.use_pep517())
-        self.cmd_opts.add_option(cmdoptions.no_use_pep517())
         self.cmd_opts.add_option(cmdoptions.check_build_deps())
 
         self.cmd_opts.add_option(cmdoptions.config_settings())
@@ -114,7 +110,6 @@ def run(self, options: Values, args: list[str]) -> int:
         )
 
         reqs = self.get_requirements(args, options, finder, session)
-        check_legacy_setup_py_options(options, reqs)
 
         wheel_cache = WheelCache(options.cache_dir)
 
@@ -142,7 +137,6 @@ def run(self, options: Values, args: list[str]) -> int:
             ignore_installed=True,
             ignore_requires_python=options.ignore_requires_python,
             upgrade_strategy="to-satisfy-only",
-            use_pep517=options.use_pep517,
         )
 
         self.trace_basic_info(finder)
diff --git a/src/pip/_internal/commands/wheel.py b/src/pip/_internal/commands/wheel.py
index 61be254912f..98d3da7f416 100644
--- a/src/pip/_internal/commands/wheel.py
+++ b/src/pip/_internal/commands/wheel.py
@@ -11,7 +11,6 @@
 from pip._internal.operations.build.build_tracker import get_build_tracker
 from pip._internal.req.req_install import (
     InstallRequirement,
-    check_legacy_setup_py_options,
 )
 from pip._internal.utils.misc import ensure_dir, normalize_path
 from pip._internal.utils.temp_dir import TempDirectory
@@ -57,7 +56,6 @@ def add_options(self) -> None:
         self.cmd_opts.add_option(cmdoptions.prefer_binary())
         self.cmd_opts.add_option(cmdoptions.no_build_isolation())
         self.cmd_opts.add_option(cmdoptions.use_pep517())
-        self.cmd_opts.add_option(cmdoptions.no_use_pep517())
         self.cmd_opts.add_option(cmdoptions.check_build_deps())
         self.cmd_opts.add_option(cmdoptions.constraints())
         self.cmd_opts.add_option(cmdoptions.editable())
@@ -76,8 +74,6 @@ def add_options(self) -> None:
         )
 
         self.cmd_opts.add_option(cmdoptions.config_settings())
-        self.cmd_opts.add_option(cmdoptions.build_options())
-        self.cmd_opts.add_option(cmdoptions.global_options())
 
         self.cmd_opts.add_option(
             "--pre",
@@ -117,7 +113,6 @@ def run(self, options: Values, args: list[str]) -> int:
         )
 
         reqs = self.get_requirements(args, options, finder, session)
-        check_legacy_setup_py_options(options, reqs)
 
         wheel_cache = WheelCache(options.cache_dir)
 
@@ -138,7 +133,6 @@ def run(self, options: Values, args: list[str]) -> int:
             options=options,
             wheel_cache=wheel_cache,
             ignore_requires_python=options.ignore_requires_python,
-            use_pep517=options.use_pep517,
         )
 
         self.trace_basic_info(finder)
@@ -159,8 +153,6 @@ def run(self, options: Values, args: list[str]) -> int:
             reqs_to_build,
             wheel_cache=wheel_cache,
             verify=(not options.no_verify),
-            build_options=options.build_options or [],
-            global_options=options.global_options or [],
         )
         for req in build_successes:
             assert req.link and req.link.is_wheel
diff --git a/src/pip/_internal/distributions/sdist.py b/src/pip/_internal/distributions/sdist.py
index e2821f89e00..f7bd7836d0e 100644
--- a/src/pip/_internal/distributions/sdist.py
+++ b/src/pip/_internal/distributions/sdist.py
@@ -20,7 +20,7 @@ class SourceDistribution(AbstractDistribution):
     """Represents a source distribution.
 
     The preparation step for these needs metadata for the packages to be
-    generated, either using PEP 517 or using the legacy `setup.py egg_info`.
+    generated.
     """
 
     @property
@@ -38,28 +38,27 @@ def prepare_distribution_metadata(
         build_isolation: bool,
         check_build_deps: bool,
     ) -> None:
-        # Load pyproject.toml, to determine whether PEP 517 is to be used
+        # Load pyproject.toml
         self.req.load_pyproject_toml()
 
         # Set up the build isolation, if this requirement should be isolated
-        should_isolate = self.req.use_pep517 and build_isolation
-        if should_isolate:
+        if build_isolation:
             # Setup an isolated environment and install the build backend static
             # requirements in it.
             self._prepare_build_backend(build_env_installer)
-            # Check that if the requirement is editable, it either supports PEP 660 or
-            # has a setup.py or a setup.cfg. This cannot be done earlier because we need
-            # to setup the build backend to verify it supports build_editable, nor can
-            # it be done later, because we want to avoid installing build requirements
-            # needlessly. Doing it here also works around setuptools generating
-            # UNKNOWN.egg-info when running get_requires_for_build_wheel on a directory
-            # without setup.py nor setup.cfg.
-            self.req.isolated_editable_sanity_check()
+            # Check that the build backend supports PEP 660. This cannot be done
+            # earlier because we need to setup the build backend to verify it
+            # supports build_editable, nor can it be done later, because we want
+            # to avoid installing build requirements needlessly.
+            self.req.editable_sanity_check()
             # Install the dynamic build requirements.
             self._install_build_reqs(build_env_installer)
+        else:
+            # When not using build isolation, we still need to check that
+            # the build backend supports PEP 660.
+            self.req.editable_sanity_check()
         # Check if the current environment provides build dependencies
-        should_check_deps = self.req.use_pep517 and check_build_deps
-        if should_check_deps:
+        if check_build_deps:
             pyproject_requires = self.req.pyproject_requires
             assert pyproject_requires is not None
             conflicting, missing = self.req.build_env.check_requirements(
diff --git a/src/pip/_internal/operations/build/metadata_legacy.py b/src/pip/_internal/operations/build/metadata_legacy.py
deleted file mode 100644
index e385b5ddf76..00000000000
--- a/src/pip/_internal/operations/build/metadata_legacy.py
+++ /dev/null
@@ -1,73 +0,0 @@
-"""Metadata generation logic for legacy source distributions."""
-
-import logging
-import os
-
-from pip._internal.build_env import BuildEnvironment
-from pip._internal.cli.spinners import open_spinner
-from pip._internal.exceptions import (
-    InstallationError,
-    InstallationSubprocessError,
-    MetadataGenerationFailed,
-)
-from pip._internal.utils.setuptools_build import make_setuptools_egg_info_args
-from pip._internal.utils.subprocess import call_subprocess
-from pip._internal.utils.temp_dir import TempDirectory
-
-logger = logging.getLogger(__name__)
-
-
-def _find_egg_info(directory: str) -> str:
-    """Find an .egg-info subdirectory in `directory`."""
-    filenames = [f for f in os.listdir(directory) if f.endswith(".egg-info")]
-
-    if not filenames:
-        raise InstallationError(f"No .egg-info directory found in {directory}")
-
-    if len(filenames) > 1:
-        raise InstallationError(
-            f"More than one .egg-info directory found in {directory}"
-        )
-
-    return os.path.join(directory, filenames[0])
-
-
-def generate_metadata(
-    build_env: BuildEnvironment,
-    setup_py_path: str,
-    source_dir: str,
-    isolated: bool,
-    details: str,
-) -> str:
-    """Generate metadata using setup.py-based defacto mechanisms.
-
-    Returns the generated metadata directory.
-    """
-    logger.debug(
-        "Running setup.py (path:%s) egg_info for package %s",
-        setup_py_path,
-        details,
-    )
-
-    egg_info_dir = TempDirectory(kind="pip-egg-info", globally_managed=True).path
-
-    args = make_setuptools_egg_info_args(
-        setup_py_path,
-        egg_info_dir=egg_info_dir,
-        no_user_config=isolated,
-    )
-
-    with build_env:
-        with open_spinner("Preparing metadata (setup.py)") as spinner:
-            try:
-                call_subprocess(
-                    args,
-                    cwd=source_dir,
-                    command_desc="python setup.py egg_info",
-                    spinner=spinner,
-                )
-            except InstallationSubprocessError as error:
-                raise MetadataGenerationFailed(package_details=details) from error
-
-    # Return the .egg-info directory.
-    return _find_egg_info(egg_info_dir)
diff --git a/src/pip/_internal/operations/build/wheel_legacy.py b/src/pip/_internal/operations/build/wheel_legacy.py
deleted file mode 100644
index 02ef8e57075..00000000000
--- a/src/pip/_internal/operations/build/wheel_legacy.py
+++ /dev/null
@@ -1,119 +0,0 @@
-from __future__ import annotations
-
-import logging
-import os.path
-
-from pip._internal.cli.spinners import open_spinner
-from pip._internal.utils.deprecation import deprecated
-from pip._internal.utils.setuptools_build import make_setuptools_bdist_wheel_args
-from pip._internal.utils.subprocess import call_subprocess, format_command_args
-
-logger = logging.getLogger(__name__)
-
-
-def format_command_result(
-    command_args: list[str],
-    command_output: str,
-) -> str:
-    """Format command information for logging."""
-    command_desc = format_command_args(command_args)
-    text = f"Command arguments: {command_desc}\n"
-
-    if not command_output:
-        text += "Command output: None"
-    elif logger.getEffectiveLevel() > logging.DEBUG:
-        text += "Command output: [use --verbose to show]"
-    else:
-        if not command_output.endswith("\n"):
-            command_output += "\n"
-        text += f"Command output:\n{command_output}"
-
-    return text
-
-
-def get_legacy_build_wheel_path(
-    names: list[str],
-    temp_dir: str,
-    name: str,
-    command_args: list[str],
-    command_output: str,
-) -> str | None:
-    """Return the path to the wheel in the temporary build directory."""
-    # Sort for determinism.
-    names = sorted(names)
-    if not names:
-        msg = f"Legacy build of wheel for {name!r} created no files.\n"
-        msg += format_command_result(command_args, command_output)
-        logger.warning(msg)
-        return None
-
-    if len(names) > 1:
-        msg = (
-            f"Legacy build of wheel for {name!r} created more than one file.\n"
-            f"Filenames (choosing first): {names}\n"
-        )
-        msg += format_command_result(command_args, command_output)
-        logger.warning(msg)
-
-    return os.path.join(temp_dir, names[0])
-
-
-def build_wheel_legacy(
-    name: str,
-    setup_py_path: str,
-    source_dir: str,
-    global_options: list[str],
-    build_options: list[str],
-    tempd: str,
-) -> str | None:
-    """Build one unpacked package using the "legacy" build process.
-
-    Returns path to wheel if successfully built. Otherwise, returns None.
-    """
-    deprecated(
-        reason=(
-            f"Building {name!r} using the legacy setup.py bdist_wheel mechanism, "
-            "which will be removed in a future version."
-        ),
-        replacement=(
-            "to use the standardized build interface by "
-            "setting the `--use-pep517` option, "
-            "(possibly combined with `--no-build-isolation`), "
-            f"or adding a `pyproject.toml` file to the source tree of {name!r}"
-        ),
-        gone_in="25.3",
-        issue=6334,
-    )
-
-    wheel_args = make_setuptools_bdist_wheel_args(
-        setup_py_path,
-        global_options=global_options,
-        build_options=build_options,
-        destination_dir=tempd,
-    )
-
-    spin_message = f"Building wheel for {name} (setup.py)"
-    with open_spinner(spin_message) as spinner:
-        logger.debug("Destination directory: %s", tempd)
-
-        try:
-            output = call_subprocess(
-                wheel_args,
-                command_desc="python setup.py bdist_wheel",
-                cwd=source_dir,
-                spinner=spinner,
-            )
-        except Exception:
-            spinner.finish("error")
-            logger.error("Failed building wheel for %s", name)
-            return None
-
-        names = os.listdir(tempd)
-        wheel_path = get_legacy_build_wheel_path(
-            names=names,
-            temp_dir=tempd,
-            name=name,
-            command_args=wheel_args,
-            command_output=output,
-        )
-        return wheel_path
diff --git a/src/pip/_internal/operations/install/editable_legacy.py b/src/pip/_internal/operations/install/editable_legacy.py
deleted file mode 100644
index 0603d3d8819..00000000000
--- a/src/pip/_internal/operations/install/editable_legacy.py
+++ /dev/null
@@ -1,48 +0,0 @@
-"""Legacy editable installation process, i.e. `setup.py develop`."""
-
-from __future__ import annotations
-
-import logging
-from collections.abc import Sequence
-
-from pip._internal.build_env import BuildEnvironment
-from pip._internal.utils.logging import indent_log
-from pip._internal.utils.setuptools_build import make_setuptools_develop_args
-from pip._internal.utils.subprocess import call_subprocess
-
-logger = logging.getLogger(__name__)
-
-
-def install_editable(
-    *,
-    global_options: Sequence[str],
-    prefix: str | None,
-    home: str | None,
-    use_user_site: bool,
-    name: str,
-    setup_py_path: str,
-    isolated: bool,
-    build_env: BuildEnvironment,
-    unpacked_source_directory: str,
-) -> None:
-    """Install a package in editable mode. Most arguments are pass-through
-    to setuptools.
-    """
-    logger.info("Running setup.py develop for %s", name)
-
-    args = make_setuptools_develop_args(
-        setup_py_path,
-        global_options=global_options,
-        no_user_config=isolated,
-        prefix=prefix,
-        home=home,
-        use_user_site=use_user_site,
-    )
-
-    with indent_log():
-        with build_env:
-            call_subprocess(
-                args,
-                command_desc="python setup.py develop",
-                cwd=unpacked_source_directory,
-            )
diff --git a/src/pip/_internal/pyproject.py b/src/pip/_internal/pyproject.py
index 5c08b60e5b5..8c2f7221c93 100644
--- a/src/pip/_internal/pyproject.py
+++ b/src/pip/_internal/pyproject.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import importlib.util
 import os
 from collections import namedtuple
 from typing import Any
@@ -30,13 +29,11 @@ def make_pyproject_path(unpacked_source_directory: str) -> str:
 
 
 def load_pyproject_toml(
-    use_pep517: bool | None, pyproject_toml: str, setup_py: str, req_name: str
-) -> BuildSystemDetails | None:
+    pyproject_toml: str, setup_py: str, req_name: str
+) -> BuildSystemDetails:
     """Load the pyproject.toml file.
 
     Parameters:
-        use_pep517 - Has the user requested PEP 517 processing? None
-                     means the user hasn't explicitly specified.
         pyproject_toml - Location of the project's pyproject.toml file
         setup_py - Location of the project's setup.py file
         req_name - The name of the requirement we're processing (for
@@ -69,57 +66,7 @@ def load_pyproject_toml(
     else:
         build_system = None
 
-    # The following cases must use PEP 517
-    # We check for use_pep517 being non-None and falsy because that means
-    # the user explicitly requested --no-use-pep517.  The value 0 as
-    # opposed to False can occur when the value is provided via an
-    # environment variable or config file option (due to the quirk of
-    # strtobool() returning an integer in pip's configuration code).
-    if has_pyproject and not has_setup:
-        if use_pep517 is not None and not use_pep517:
-            raise InstallationError(
-                "Disabling PEP 517 processing is invalid: "
-                "project does not have a setup.py"
-            )
-        use_pep517 = True
-    elif build_system and "build-backend" in build_system:
-        if use_pep517 is not None and not use_pep517:
-            raise InstallationError(
-                "Disabling PEP 517 processing is invalid: "
-                "project specifies a build backend of {} "
-                "in pyproject.toml".format(build_system["build-backend"])
-            )
-        use_pep517 = True
-
-    # If we haven't worked out whether to use PEP 517 yet,
-    # and the user hasn't explicitly stated a preference,
-    # we do so if the project has a pyproject.toml file
-    # or if we cannot import setuptools or wheels.
-
-    # We fallback to PEP 517 when without setuptools or without the wheel package,
-    # so setuptools can be installed as a default build backend.
-    # For more info see:
-    # https://discuss.python.org/t/pip-without-setuptools-could-the-experience-be-improved/11810/9
-    # https://github.com/pypa/pip/issues/8559
-    elif use_pep517 is None:
-        use_pep517 = (
-            has_pyproject
-            or not importlib.util.find_spec("setuptools")
-            or not importlib.util.find_spec("wheel")
-        )
-
-    # At this point, we know whether we're going to use PEP 517.
-    assert use_pep517 is not None
-
-    # If we're using the legacy code path, there is nothing further
-    # for us to do here.
-    if not use_pep517:
-        return None
-
     if build_system is None:
-        # Either the user has a pyproject.toml with no build-system
-        # section, or the user has no pyproject.toml, but has opted in
-        # explicitly via --use-pep517.
         # In the absence of any explicit backend specification, we
         # assume the setuptools backend that most closely emulates the
         # traditional direct setup.py execution, and require wheel and
@@ -130,12 +77,6 @@ def load_pyproject_toml(
             "build-backend": "setuptools.build_meta:__legacy__",
         }
 
-    # If we're using PEP 517, we have build system information (either
-    # from pyproject.toml, or defaulted by the code above).
-    # Note that at this point, we do not know if the user has actually
-    # specified a backend, though.
-    assert build_system is not None
-
     # Ensure that the build-system section in pyproject.toml conforms
     # to PEP 518.
 
diff --git a/src/pip/_internal/req/__init__.py b/src/pip/_internal/req/__init__.py
index e5050ee588b..5fc8752d8e4 100644
--- a/src/pip/_internal/req/__init__.py
+++ b/src/pip/_internal/req/__init__.py
@@ -2,7 +2,7 @@
 
 import collections
 import logging
-from collections.abc import Generator, Sequence
+from collections.abc import Generator
 from dataclasses import dataclass
 
 from pip._internal.cli.progress_bars import BarType, get_install_progress_renderer
@@ -37,7 +37,6 @@ def _validate_requirements(
 
 def install_given_reqs(
     requirements: list[InstallRequirement],
-    global_options: Sequence[str],
     root: str | None,
     home: str | None,
     prefix: str | None,
@@ -83,7 +82,6 @@ def install_given_reqs(
 
             try:
                 requirement.install(
-                    global_options,
                     root=root,
                     home=home,
                     prefix=prefix,
diff --git a/src/pip/_internal/req/constructors.py b/src/pip/_internal/req/constructors.py
index 76c8c38499a..f8531e113a3 100644
--- a/src/pip/_internal/req/constructors.py
+++ b/src/pip/_internal/req/constructors.py
@@ -225,9 +225,7 @@ def install_req_from_editable(
     editable_req: str,
     comes_from: InstallRequirement | str | None = None,
     *,
-    use_pep517: bool | None = None,
     isolated: bool = False,
-    global_options: list[str] | None = None,
     hash_options: dict[str, list[str]] | None = None,
     constraint: bool = False,
     user_supplied: bool = False,
@@ -244,9 +242,7 @@ def install_req_from_editable(
         permit_editable_wheels=permit_editable_wheels,
         link=parts.link,
         constraint=constraint,
-        use_pep517=use_pep517,
         isolated=isolated,
-        global_options=global_options,
         hash_options=hash_options,
         config_settings=config_settings,
         extras=parts.extras,
@@ -389,9 +385,7 @@ def install_req_from_line(
     name: str,
     comes_from: str | InstallRequirement | None = None,
     *,
-    use_pep517: bool | None = None,
     isolated: bool = False,
-    global_options: list[str] | None = None,
     hash_options: dict[str, list[str]] | None = None,
     constraint: bool = False,
     line_source: str | None = None,
@@ -411,9 +405,7 @@ def install_req_from_line(
         comes_from,
         link=parts.link,
         markers=parts.markers,
-        use_pep517=use_pep517,
         isolated=isolated,
-        global_options=global_options,
         hash_options=hash_options,
         config_settings=config_settings,
         constraint=constraint,
@@ -426,7 +418,6 @@ def install_req_from_req_string(
     req_string: str,
     comes_from: InstallRequirement | None = None,
     isolated: bool = False,
-    use_pep517: bool | None = None,
     user_supplied: bool = False,
 ) -> InstallRequirement:
     try:
@@ -455,7 +446,6 @@ def install_req_from_req_string(
         req,
         comes_from,
         isolated=isolated,
-        use_pep517=use_pep517,
         user_supplied=user_supplied,
     )
 
@@ -463,7 +453,6 @@ def install_req_from_req_string(
 def install_req_from_parsed_requirement(
     parsed_req: ParsedRequirement,
     isolated: bool = False,
-    use_pep517: bool | None = None,
     user_supplied: bool = False,
     config_settings: dict[str, str | list[str]] | None = None,
 ) -> InstallRequirement:
@@ -471,7 +460,6 @@ def install_req_from_parsed_requirement(
         req = install_req_from_editable(
             parsed_req.requirement,
             comes_from=parsed_req.comes_from,
-            use_pep517=use_pep517,
             constraint=parsed_req.constraint,
             isolated=isolated,
             user_supplied=user_supplied,
@@ -482,13 +470,7 @@ def install_req_from_parsed_requirement(
         req = install_req_from_line(
             parsed_req.requirement,
             comes_from=parsed_req.comes_from,
-            use_pep517=use_pep517,
             isolated=isolated,
-            global_options=(
-                parsed_req.options.get("global_options", [])
-                if parsed_req.options
-                else []
-            ),
             hash_options=(
                 parsed_req.options.get("hashes", {}) if parsed_req.options else {}
             ),
@@ -509,9 +491,7 @@ def install_req_from_link_and_ireq(
         editable=ireq.editable,
         link=link,
         markers=ireq.markers,
-        use_pep517=ireq.use_pep517,
         isolated=ireq.isolated,
-        global_options=ireq.global_options,
         hash_options=ireq.hash_options,
         config_settings=ireq.config_settings,
         user_supplied=ireq.user_supplied,
@@ -532,9 +512,7 @@ def install_req_drop_extras(ireq: InstallRequirement) -> InstallRequirement:
         editable=ireq.editable,
         link=ireq.link,
         markers=ireq.markers,
-        use_pep517=ireq.use_pep517,
         isolated=ireq.isolated,
-        global_options=ireq.global_options,
         hash_options=ireq.hash_options,
         constraint=ireq.constraint,
         extras=[],
diff --git a/src/pip/_internal/req/req_file.py b/src/pip/_internal/req/req_file.py
index 0aad0a36602..a4f54b438f2 100644
--- a/src/pip/_internal/req/req_file.py
+++ b/src/pip/_internal/req/req_file.py
@@ -65,7 +65,6 @@
 
 # options to be passed to requirements
 SUPPORTED_OPTIONS_REQ: list[Callable[..., optparse.Option]] = [
-    cmdoptions.global_options,
     cmdoptions.hash,
     cmdoptions.config_settings,
 ]
diff --git a/src/pip/_internal/req/req_install.py b/src/pip/_internal/req/req_install.py
index c9f6bff17e8..195f13e3851 100644
--- a/src/pip/_internal/req/req_install.py
+++ b/src/pip/_internal/req/req_install.py
@@ -7,7 +7,7 @@
 import sys
 import uuid
 import zipfile
-from collections.abc import Collection, Iterable, Sequence
+from collections.abc import Collection, Iterable
 from optparse import Values
 from pathlib import Path
 from typing import Any
@@ -34,12 +34,6 @@
 from pip._internal.models.link import Link
 from pip._internal.operations.build.metadata import generate_metadata
 from pip._internal.operations.build.metadata_editable import generate_editable_metadata
-from pip._internal.operations.build.metadata_legacy import (
-    generate_metadata as generate_metadata_legacy,
-)
-from pip._internal.operations.install.editable_legacy import (
-    install_editable as install_editable_legacy,
-)
 from pip._internal.operations.install.wheel import install_wheel
 from pip._internal.pyproject import load_pyproject_toml, make_pyproject_path
 from pip._internal.req.req_uninstall import UninstallPathSet
@@ -79,10 +73,8 @@ def __init__(
         editable: bool = False,
         link: Link | None = None,
         markers: Marker | None = None,
-        use_pep517: bool | None = None,
         isolated: bool = False,
         *,
-        global_options: list[str] | None = None,
         hash_options: dict[str, list[str]] | None = None,
         config_settings: dict[str, str | list[str]] | None = None,
         constraint: bool = False,
@@ -149,7 +141,6 @@ def __init__(
         # Set to True after successful installation
         self.install_succeeded: bool | None = None
         # Supplied options
-        self.global_options = global_options if global_options else []
         self.hash_options = hash_options if hash_options else {}
         self.config_settings = config_settings
         # Set to True after successful preparation of this requirement
@@ -177,23 +168,6 @@ def __init__(
         # The PEP 517 backend we should use to build the project
         self.pep517_backend: BuildBackendHookCaller | None = None
 
-        # Are we using PEP 517 for this requirement?
-        # After pyproject.toml has been loaded, the only valid values are True
-        # and False. Before loading, None is valid (meaning "use the default").
-        # Setting an explicit value before loading pyproject.toml is supported,
-        # but after loading this flag should be treated as read only.
-        self.use_pep517 = use_pep517
-
-        # If config settings are provided, enforce PEP 517.
-        if self.config_settings:
-            if self.use_pep517 is False:
-                logger.warning(
-                    "--no-use-pep517 ignored for %s "
-                    "because --config-settings are specified.",
-                    self,
-                )
-            self.use_pep517 = True
-
         # This requirement needs more preparation before it can be built
         self.needs_more_preparation = False
 
@@ -250,8 +224,6 @@ def name(self) -> str | None:
 
     @functools.cached_property
     def supports_pyproject_editable(self) -> bool:
-        if not self.use_pep517:
-            return False
         assert self.pep517_backend
         with self.build_env:
             runner = runner_with_spinner_message(
@@ -492,13 +464,6 @@ def setup_py_path(self) -> str:
 
         return setup_py
 
-    @property
-    def setup_cfg_path(self) -> str:
-        assert self.source_dir, f"No source dir for {self}"
-        setup_cfg = os.path.join(self.unpacked_source_directory, "setup.cfg")
-
-        return setup_cfg
-
     @property
     def pyproject_toml_path(self) -> str:
         assert self.source_dir, f"No source dir for {self}"
@@ -508,20 +473,12 @@ def load_pyproject_toml(self) -> None:
         """Load the pyproject.toml file.
 
         After calling this routine, all of the attributes related to PEP 517
-        processing for this requirement have been set. In particular, the
-        use_pep517 attribute can be used to determine whether we should
-        follow the PEP 517 or legacy (setup.py) code path.
+        processing for this requirement have been set.
         """
         pyproject_toml_data = load_pyproject_toml(
-            self.use_pep517, self.pyproject_toml_path, self.setup_py_path, str(self)
+            self.pyproject_toml_path, self.setup_py_path, str(self)
         )
-
-        if pyproject_toml_data is None:
-            assert not self.config_settings
-            self.use_pep517 = False
-            return
-
-        self.use_pep517 = True
+        assert pyproject_toml_data
         requires, backend, check, backend_path = pyproject_toml_data
         self.requirements_to_check = check
         self.pyproject_requires = requires
@@ -532,23 +489,15 @@ def load_pyproject_toml(self) -> None:
             backend_path=backend_path,
         )
 
-    def isolated_editable_sanity_check(self) -> None:
+    def editable_sanity_check(self) -> None:
         """Check that an editable requirement if valid for use with PEP 517/518.
 
-        This verifies that an editable that has a pyproject.toml either supports PEP 660
-        or as a setup.py or a setup.cfg
+        This verifies that an editable has a build backend that supports PEP 660.
         """
-        if (
-            self.editable
-            and self.use_pep517
-            and not self.supports_pyproject_editable
-            and not os.path.isfile(self.setup_py_path)
-            and not os.path.isfile(self.setup_cfg_path)
-        ):
+        if self.editable and not self.supports_pyproject_editable:
             raise InstallationError(
-                f"Project {self} has a 'pyproject.toml' and its build "
-                f"backend is missing the 'build_editable' hook. Since it does not "
-                f"have a 'setup.py' nor a 'setup.cfg', "
+                f"Project {self} uses a build backend "
+                f"that is missing the 'build_editable' hook, so "
                 f"it cannot be installed in editable mode. "
                 f"Consider using a build backend that supports PEP 660."
             )
@@ -562,30 +511,21 @@ def prepare_metadata(self) -> None:
         assert self.source_dir, f"No source dir for {self}"
         details = self.name or f"from {self.link}"
 
-        if self.use_pep517:
-            assert self.pep517_backend is not None
-            if (
-                self.editable
-                and self.permit_editable_wheels
-                and self.supports_pyproject_editable
-            ):
-                self.metadata_directory = generate_editable_metadata(
-                    build_env=self.build_env,
-                    backend=self.pep517_backend,
-                    details=details,
-                )
-            else:
-                self.metadata_directory = generate_metadata(
-                    build_env=self.build_env,
-                    backend=self.pep517_backend,
-                    details=details,
-                )
+        assert self.pep517_backend is not None
+        if (
+            self.editable
+            and self.permit_editable_wheels
+            and self.supports_pyproject_editable
+        ):
+            self.metadata_directory = generate_editable_metadata(
+                build_env=self.build_env,
+                backend=self.pep517_backend,
+                details=details,
+            )
         else:
-            self.metadata_directory = generate_metadata_legacy(
+            self.metadata_directory = generate_metadata(
                 build_env=self.build_env,
-                setup_py_path=self.setup_py_path,
-                source_dir=self.unpacked_source_directory,
-                isolated=self.isolated,
+                backend=self.pep517_backend,
                 details=details,
             )
 
@@ -809,7 +749,6 @@ def archive(self, build_dir: str | None) -> None:
 
     def install(
         self,
-        global_options: Sequence[str] | None = None,
         root: str | None = None,
         home: str | None = None,
         prefix: str | None = None,
@@ -827,43 +766,6 @@ def install(
             prefix=prefix,
         )
 
-        if self.editable and not self.is_wheel:
-            deprecated(
-                reason=(
-                    f"Legacy editable install of {self} (setup.py develop) "
-                    "is deprecated."
-                ),
-                replacement=(
-                    "to add a pyproject.toml or enable --use-pep517, "
-                    "and use setuptools >= 64. "
-                    "If the resulting installation is not behaving as expected, "
-                    "try using --config-settings editable_mode=compat. "
-                    "Please consult the setuptools documentation for more information"
-                ),
-                gone_in="25.3",
-                issue=11457,
-            )
-            if self.config_settings:
-                logger.warning(
-                    "--config-settings ignored for legacy editable install of %s. "
-                    "Consider upgrading to a version of setuptools "
-                    "that supports PEP 660 (>= 64).",
-                    self,
-                )
-            install_editable_legacy(
-                global_options=global_options if global_options is not None else [],
-                prefix=prefix,
-                home=home,
-                use_user_site=use_user_site,
-                name=self.req.name,
-                setup_py_path=self.setup_py_path,
-                isolated=self.isolated,
-                build_env=self.build_env,
-                unpacked_source_directory=self.unpacked_source_directory,
-            )
-            self.install_succeeded = True
-            return
-
         assert self.is_wheel
         assert self.local_file_path
 
@@ -915,23 +817,3 @@ def _has_option(options: Values, reqs: list[InstallRequirement], option: str) ->
         if getattr(req, option, None):
             return True
     return False
-
-
-def check_legacy_setup_py_options(
-    options: Values,
-    reqs: list[InstallRequirement],
-) -> None:
-    has_build_options = _has_option(options, reqs, "build_options")
-    has_global_options = _has_option(options, reqs, "global_options")
-    if has_build_options or has_global_options:
-        deprecated(
-            reason="--build-option and --global-option are deprecated.",
-            issue=11859,
-            replacement="to use --config-settings",
-            gone_in="25.3",
-        )
-        logger.warning(
-            "Implying --no-binary=:all: due to the presence of "
-            "--build-option / --global-option. "
-        )
-        options.format_control.disallow_binaries()
diff --git a/src/pip/_internal/resolution/resolvelib/candidates.py b/src/pip/_internal/resolution/resolvelib/candidates.py
index 5a4ab8154d9..108942768f9 100644
--- a/src/pip/_internal/resolution/resolvelib/candidates.py
+++ b/src/pip/_internal/resolution/resolvelib/candidates.py
@@ -69,10 +69,8 @@ def make_install_req_from_link(
         line,
         user_supplied=template.user_supplied,
         comes_from=template.comes_from,
-        use_pep517=template.use_pep517,
         isolated=template.isolated,
         constraint=template.constraint,
-        global_options=template.global_options,
         hash_options=template.hash_options,
         config_settings=template.config_settings,
     )
@@ -90,11 +88,9 @@ def make_install_req_from_editable(
         link.url,
         user_supplied=template.user_supplied,
         comes_from=template.comes_from,
-        use_pep517=template.use_pep517,
         isolated=template.isolated,
         constraint=template.constraint,
         permit_editable_wheels=template.permit_editable_wheels,
-        global_options=template.global_options,
         hash_options=template.hash_options,
         config_settings=template.config_settings,
     )
@@ -115,10 +111,8 @@ def _make_install_req_from_dist(
         line,
         user_supplied=template.user_supplied,
         comes_from=template.comes_from,
-        use_pep517=template.use_pep517,
         isolated=template.isolated,
         constraint=template.constraint,
-        global_options=template.global_options,
         hash_options=template.hash_options,
         config_settings=template.config_settings,
     )
diff --git a/src/pip/_internal/utils/setuptools_build.py b/src/pip/_internal/utils/setuptools_build.py
deleted file mode 100644
index 1b8c7a1c21f..00000000000
--- a/src/pip/_internal/utils/setuptools_build.py
+++ /dev/null
@@ -1,149 +0,0 @@
-from __future__ import annotations
-
-import sys
-import textwrap
-from collections.abc import Sequence
-
-# Shim to wrap setup.py invocation with setuptools
-# Note that __file__ is handled via two {!r} *and* %r, to ensure that paths on
-# Windows are correctly handled (it should be "C:\\Users" not "C:\Users").
-_SETUPTOOLS_SHIM = textwrap.dedent(
-    """
-    exec(compile('''
-    # This is <pip-setuptools-caller> -- a caller that pip uses to run setup.py
-    #
-    # - It imports setuptools before invoking setup.py, to enable projects that directly
-    #   import from `distutils.core` to work with newer packaging standards.
-    # - It provides a clear error message when setuptools is not installed.
-    # - It sets `sys.argv[0]` to the underlying `setup.py`, when invoking `setup.py` so
-    #   setuptools doesn't think the script is `-c`. This avoids the following warning:
-    #     manifest_maker: standard file '-c' not found".
-    # - It generates a shim setup.py, for handling setup.cfg-only projects.
-    import os, sys, tokenize, traceback
-
-    try:
-        import setuptools
-    except ImportError:
-        print(
-            "ERROR: Can not execute `setup.py` since setuptools failed to import in "
-            "the build environment with exception:",
-            file=sys.stderr,
-        )
-        traceback.print_exc()
-        sys.exit(1)
-
-    __file__ = %r
-    sys.argv[0] = __file__
-
-    if os.path.exists(__file__):
-        filename = __file__
-        with tokenize.open(__file__) as f:
-            setup_py_code = f.read()
-    else:
-        filename = "<auto-generated setuptools caller>"
-        setup_py_code = "from setuptools import setup; setup()"
-
-    exec(compile(setup_py_code, filename, "exec"))
-    ''' % ({!r},), "<pip-setuptools-caller>", "exec"))
-    """
-).rstrip()
-
-
-def make_setuptools_shim_args(
-    setup_py_path: str,
-    global_options: Sequence[str] | None = None,
-    no_user_config: bool = False,
-    unbuffered_output: bool = False,
-) -> list[str]:
-    """
-    Get setuptools command arguments with shim wrapped setup file invocation.
-
-    :param setup_py_path: The path to setup.py to be wrapped.
-    :param global_options: Additional global options.
-    :param no_user_config: If True, disables personal user configuration.
-    :param unbuffered_output: If True, adds the unbuffered switch to the
-     argument list.
-    """
-    args = [sys.executable]
-    if unbuffered_output:
-        args += ["-u"]
-    args += ["-c", _SETUPTOOLS_SHIM.format(setup_py_path)]
-    if global_options:
-        args += global_options
-    if no_user_config:
-        args += ["--no-user-cfg"]
-    return args
-
-
-def make_setuptools_bdist_wheel_args(
-    setup_py_path: str,
-    global_options: Sequence[str],
-    build_options: Sequence[str],
-    destination_dir: str,
-) -> list[str]:
-    # NOTE: Eventually, we'd want to also -S to the flags here, when we're
-    # isolating. Currently, it breaks Python in virtualenvs, because it
-    # relies on site.py to find parts of the standard library outside the
-    # virtualenv.
-    args = make_setuptools_shim_args(
-        setup_py_path, global_options=global_options, unbuffered_output=True
-    )
-    args += ["bdist_wheel", "-d", destination_dir]
-    args += build_options
-    return args
-
-
-def make_setuptools_clean_args(
-    setup_py_path: str,
-    global_options: Sequence[str],
-) -> list[str]:
-    args = make_setuptools_shim_args(
-        setup_py_path, global_options=global_options, unbuffered_output=True
-    )
-    args += ["clean", "--all"]
-    return args
-
-
-def make_setuptools_develop_args(
-    setup_py_path: str,
-    *,
-    global_options: Sequence[str],
-    no_user_config: bool,
-    prefix: str | None,
-    home: str | None,
-    use_user_site: bool,
-) -> list[str]:
-    assert not (use_user_site and prefix)
-
-    args = make_setuptools_shim_args(
-        setup_py_path,
-        global_options=global_options,
-        no_user_config=no_user_config,
-    )
-
-    args += ["develop", "--no-deps"]
-
-    if prefix:
-        args += ["--prefix", prefix]
-    if home is not None:
-        args += ["--install-dir", home]
-
-    if use_user_site:
-        args += ["--user", "--prefix="]
-
-    return args
-
-
-def make_setuptools_egg_info_args(
-    setup_py_path: str,
-    egg_info_dir: str | None,
-    no_user_config: bool,
-) -> list[str]:
-    args = make_setuptools_shim_args(setup_py_path, no_user_config=no_user_config)
-
-    args += ["egg_info"]
-
-    if egg_info_dir:
-        args += ["--egg-base", egg_info_dir]
-
-    return args
diff --git a/src/pip/_internal/wheel_builder.py b/src/pip/_internal/wheel_builder.py
index c5d260700af..3e1b783d71b 100644
--- a/src/pip/_internal/wheel_builder.py
+++ b/src/pip/_internal/wheel_builder.py
@@ -18,12 +18,9 @@
 from pip._internal.models.wheel import Wheel
 from pip._internal.operations.build.wheel import build_wheel_pep517
 from pip._internal.operations.build.wheel_editable import build_wheel_editable
-from pip._internal.operations.build.wheel_legacy import build_wheel_legacy
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.logging import indent_log
 from pip._internal.utils.misc import ensure_dir, hash_file
-from pip._internal.utils.setuptools_build import make_setuptools_clean_args
-from pip._internal.utils.subprocess import call_subprocess
 from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.utils.urls import path_to_url
 from pip._internal.vcs import vcs
@@ -43,37 +40,12 @@ def _contains_egg_info(s: str) -> bool:
     return bool(_egg_info_re.search(s))
 
 
-def _should_build(
-    req: InstallRequirement,
-) -> bool:
-    """Return whether an InstallRequirement should be built into a wheel."""
-    assert not req.constraint
-
-    if req.is_wheel:
-        return False
-
-    assert req.source_dir
-
-    if req.editable:
-        # we only build PEP 660 editable requirements
-        return req.supports_pyproject_editable
-
-    return True
-
-
-def should_build_for_install_command(
-    req: InstallRequirement,
-) -> bool:
-    return _should_build(req)
-
-
 def _should_cache(
     req: InstallRequirement,
 ) -> bool | None:
     """
     Return whether a built InstallRequirement can be stored in the persistent
-    wheel cache, assuming the wheel cache is available, and _should_build()
-    has determined a wheel needs to be built.
+    wheel cache, assuming the wheel cache is available.
     """
     if req.editable or not req.source_dir:
         # never cache editable requirements
@@ -148,8 +120,6 @@ def _build_one(
     req: InstallRequirement,
     output_dir: str,
     verify: bool,
-    build_options: list[str],
-    global_options: list[str],
     editable: bool,
 ) -> str | None:
     """Build one wheel.
@@ -170,9 +140,7 @@ def _build_one(
 
     # Install build deps into temporary directory (PEP 518)
     with req.build_env:
-        wheel_path = _build_one_inside_env(
-            req, output_dir, build_options, global_options, editable
-        )
+        wheel_path = _build_one_inside_env(req, output_dir, editable)
     if wheel_path and verify:
         try:
             _verify_one(req, wheel_path)
@@ -185,44 +153,24 @@ def _build_one(
 def _build_one_inside_env(
     req: InstallRequirement,
     output_dir: str,
-    build_options: list[str],
-    global_options: list[str],
     editable: bool,
 ) -> str | None:
     with TempDirectory(kind="wheel") as temp_dir:
         assert req.name
-        if req.use_pep517:
-            assert req.metadata_directory
-            assert req.pep517_backend
-            if global_options:
-                logger.warning(
-                    "Ignoring --global-option when building %s using PEP 517", req.name
-                )
-            if build_options:
-                logger.warning(
-                    "Ignoring --build-option when building %s using PEP 517", req.name
-                )
-            if editable:
-                wheel_path = build_wheel_editable(
-                    name=req.name,
-                    backend=req.pep517_backend,
-                    metadata_directory=req.metadata_directory,
-                    tempd=temp_dir.path,
-                )
-            else:
-                wheel_path = build_wheel_pep517(
-                    name=req.name,
-                    backend=req.pep517_backend,
-                    metadata_directory=req.metadata_directory,
-                    tempd=temp_dir.path,
-                )
+        assert req.metadata_directory
+        assert req.pep517_backend
+        if editable:
+            wheel_path = build_wheel_editable(
+                name=req.name,
+                backend=req.pep517_backend,
+                metadata_directory=req.metadata_directory,
+                tempd=temp_dir.path,
+            )
         else:
-            wheel_path = build_wheel_legacy(
+            wheel_path = build_wheel_pep517(
                 name=req.name,
-                setup_py_path=req.setup_py_path,
-                source_dir=req.unpacked_source_directory,
-                global_options=global_options,
-                build_options=build_options,
+                backend=req.pep517_backend,
+                metadata_directory=req.metadata_directory,
                 tempd=temp_dir.path,
             )
 
@@ -247,35 +195,13 @@ def _build_one_inside_env(
                     req.name,
                     e,
                 )
-        # Ignore return, we can't do anything else useful.
-        if not req.use_pep517:
-            _clean_one_legacy(req, global_options)
         return None
 
 
-def _clean_one_legacy(req: InstallRequirement, global_options: list[str]) -> bool:
-    clean_args = make_setuptools_clean_args(
-        req.setup_py_path,
-        global_options=global_options,
-    )
-
-    logger.info("Running setup.py clean for %s", req.name)
-    try:
-        call_subprocess(
-            clean_args, command_desc="python setup.py clean", cwd=req.source_dir
-        )
-        return True
-    except Exception:
-        logger.error("Failed cleaning build dir for %s", req.name)
-        return False
-
-
 def build(
     requirements: Iterable[InstallRequirement],
     wheel_cache: WheelCache,
     verify: bool,
-    build_options: list[str],
-    global_options: list[str],
 ) -> BuildResult:
     """Build wheels.
 
@@ -300,8 +226,6 @@ def build(
                 req,
                 cache_dir,
                 verify,
-                build_options,
-                global_options,
                 req.editable and req.permit_editable_wheels,
             )
             if wheel_file:
diff --git a/tests/data/packages/SetupPyUTF8/setup.py b/tests/data/packages/SetupPyUTF8/setup.py
index bd9fd2a294b..026d3a215e6 100644
--- a/tests/data/packages/SetupPyUTF8/setup.py
+++ b/tests/data/packages/SetupPyUTF8/setup.py
@@ -1,4 +1,4 @@
-from distutils.core import setup
+from setuptools import setup
 
 setup(
     name="SetupPyUTF8",
diff --git a/tests/data/src/chattymodule/backend.py b/tests/data/src/chattymodule/backend.py
new file mode 100644
index 00000000000..5993b53f607
--- /dev/null
+++ b/tests/data/src/chattymodule/backend.py
@@ -0,0 +1,23 @@
+import os
+import sys
+
+from setuptools import build_meta
+from setuptools.build_meta import *
+
+
+def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
+    if config_settings and "fail" in config_settings:
+        print("I DIE, I DIE in prepare_metadata_for_build_wheel")
+        sys.exit(1)
+    print("HELLO FROM CHATTYMODULE prepare_metadata_for_build_wheel")
+    return build_meta.prepare_metadata_for_build_wheel(
+        metadata_directory, config_settings
+    )
+
+
+def build_wheel(wheel_directory, config_settings=None, metadata_directory=None):
+    if config_settings and "fail" in config_settings:
+        print("I DIE, I DIE in build_wheel")
+        sys.exit(1)
+    print("HELLO FROM CHATTYMODULE build_wheel")
+    return build_meta.build_wheel(wheel_directory, config_settings, metadata_directory)
diff --git a/tests/data/src/chattymodule/pyproject.toml b/tests/data/src/chattymodule/pyproject.toml
new file mode 100644
index 00000000000..54de20d46fc
--- /dev/null
+++ b/tests/data/src/chattymodule/pyproject.toml
@@ -0,0 +1,11 @@
+[build-system]
+requires = ["setuptools"]
+build-backend = "backend"
+backend-path = ["."]
+
+[project]
+name = "chattymodule"
+version = "0.0.1"
+
+[tool.setuptools]
+py-modules = ["chattymodule"]
diff --git a/tests/data/src/chattymodule/setup.cfg b/tests/data/src/chattymodule/setup.cfg
deleted file mode 100644
index 79bc67848ff..00000000000
--- a/tests/data/src/chattymodule/setup.cfg
+++ /dev/null
@@ -1,5 +0,0 @@
-[bdist_wheel]
-# This flag says that the code is written to work on both Python 2 and Python
-# 3. If at all possible, it is good practice to do this. If you cannot, you
-# will need to generate wheels for each Python version that you support.
-universal=1
diff --git a/tests/data/src/chattymodule/setup.py b/tests/data/src/chattymodule/setup.py
deleted file mode 100644
index 9f411b6fdff..00000000000
--- a/tests/data/src/chattymodule/setup.py
+++ /dev/null
@@ -1,22 +0,0 @@
-# A chatty setup.py for testing pip subprocess output handling
-
-import os
-import sys
-
-from setuptools import setup
-
-print(f"HELLO FROM CHATTYMODULE {sys.argv[1]}")
-print(sys.argv)
-print(sys.executable)
-print(sys.version)
-
-if "--fail" in sys.argv:
-    print("I DIE, I DIE")
-    sys.exit(1)
-
-setup(
-    name="chattymodule",
-    version="0.0.1",
-    description="A sample Python project with a single module",
-    py_modules=["chattymodule"],
-)
diff --git a/tests/functional/test_check.py b/tests/functional/test_check.py
index 06ed1b08eac..656d5ac866b 100644
--- a/tests/functional/test_check.py
+++ b/tests/functional/test_check.py
@@ -34,7 +34,9 @@ def test_basic_check_missing_dependency(script: PipTestEnvironment) -> None:
         install_requires=["missing==0.1"],
     )
     # Let's install pkga without its dependency
-    res = script.pip("install", "--no-index", pkga_path, "--no-deps")
+    res = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkga_path, "--no-deps"
+    )
     assert "Successfully installed pkga-1.0" in res.stdout, str(res)
 
     result = script.pip("check", expect_error=True)
@@ -53,7 +55,9 @@ def test_basic_check_broken_dependency(script: PipTestEnvironment) -> None:
         install_requires=["broken>=1.0"],
     )
     # Let's install pkga without its dependency
-    res = script.pip("install", "--no-index", pkga_path, "--no-deps")
+    res = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkga_path, "--no-deps"
+    )
     assert "Successfully installed pkga-1.0" in res.stdout, str(res)
 
     # Setup broken==0.1
@@ -65,6 +69,7 @@ def test_basic_check_broken_dependency(script: PipTestEnvironment) -> None:
     # Let's install broken==0.1
     res = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         broken_path,
         "--no-warn-conflicts",
@@ -88,7 +93,9 @@ def test_basic_check_broken_dependency_and_missing_dependency(
         install_requires=["broken>=1.0"],
     )
     # Let's install pkga without its dependency
-    res = script.pip("install", "--no-index", pkga_path, "--no-deps")
+    res = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkga_path, "--no-deps"
+    )
     assert "Successfully installed pkga-1.0" in res.stdout, str(res)
 
     # Setup broken==0.1
@@ -99,7 +106,9 @@ def test_basic_check_broken_dependency_and_missing_dependency(
         install_requires=["missing"],
     )
     # Let's install broken==0.1
-    res = script.pip("install", "--no-index", broken_path, "--no-deps")
+    res = script.pip(
+        "install", "--no-build-isolation", "--no-index", broken_path, "--no-deps"
+    )
     assert "Successfully installed broken-0.1" in res.stdout, str(res)
 
     result = script.pip("check", expect_error=True)
@@ -122,7 +131,9 @@ def test_check_complicated_name_missing(script: PipTestEnvironment) -> None:
     )
 
     # Without dependency
-    result = script.pip("install", "--no-index", package_a_path, "--no-deps")
+    result = script.pip(
+        "install", "--no-build-isolation", "--no-index", package_a_path, "--no-deps"
+    )
     assert (
         "Successfully installed package_A-1.0" in result.stdout
         or "Successfully installed package-A-1.0" in result.stdout
@@ -148,7 +159,9 @@ def test_check_complicated_name_broken(script: PipTestEnvironment) -> None:
     )
 
     # With broken dependency
-    result = script.pip("install", "--no-index", package_a_path, "--no-deps")
+    result = script.pip(
+        "install", "--no-build-isolation", "--no-index", package_a_path, "--no-deps"
+    )
     assert (
         "Successfully installed package_A-1.0" in result.stdout
         or "Successfully installed package-A-1.0" in result.stdout
@@ -156,6 +169,7 @@ def test_check_complicated_name_broken(script: PipTestEnvironment) -> None:
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         dependency_b_path_incompatible,
         "--no-deps",
@@ -184,7 +198,9 @@ def test_check_complicated_name_clean(script: PipTestEnvironment) -> None:
         version="1.0",
     )
 
-    result = script.pip("install", "--no-index", package_a_path, "--no-deps")
+    result = script.pip(
+        "install", "--no-build-isolation", "--no-index", package_a_path, "--no-deps"
+    )
     assert (
         "Successfully installed package_A-1.0" in result.stdout
         or "Successfully installed package-A-1.0" in result.stdout
@@ -192,6 +208,7 @@ def test_check_complicated_name_clean(script: PipTestEnvironment) -> None:
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         dependency_b_path,
         "--no-deps",
@@ -215,7 +232,9 @@ def test_check_considers_conditional_reqs(script: PipTestEnvironment) -> None:
         ],
     )
 
-    result = script.pip("install", "--no-index", package_a_path, "--no-deps")
+    result = script.pip(
+        "install", "--no-build-isolation", "--no-index", package_a_path, "--no-deps"
+    )
     assert (
         "Successfully installed package_A-1.0" in result.stdout
         or "Successfully installed package-A-1.0" in result.stdout
@@ -238,7 +257,9 @@ def test_check_development_versions_are_also_considered(
         install_requires=["depend>=1.0"],
     )
     # Let's install pkga without its dependency
-    res = script.pip("install", "--no-index", pkga_path, "--no-deps")
+    res = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkga_path, "--no-deps"
+    )
     assert "Successfully installed pkga-1.0" in res.stdout, str(res)
 
     # Setup depend==1.1.0.dev0
@@ -250,6 +271,7 @@ def test_check_development_versions_are_also_considered(
     # Let's install depend==1.1.0.dev0
     res = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         depend_path,
         "--no-warn-conflicts",
diff --git a/tests/functional/test_cli.py b/tests/functional/test_cli.py
index 6d2e2a12935..02429eb9a4d 100644
--- a/tests/functional/test_cli.py
+++ b/tests/functional/test_cli.py
@@ -45,7 +45,9 @@ def test_entrypoints_work(entrypoint: str, script: PipTestEnvironment) -> None:
     )
 
     # expect_temp because pip install will generate fake_pkg.egg-info
-    script.pip("install", "-vvv", str(fake_pkg), expect_temp=True)
+    script.pip(
+        "install", "--no-build-isolation", "-vvv", str(fake_pkg), expect_temp=True
+    )
     result = script.pip("-V")
     result2 = script.run("fake_pip", "-V", allow_stderr_warning=True)
     assert result.stdout == result2.stdout
diff --git a/tests/functional/test_completion.py b/tests/functional/test_completion.py
index f0396aa0c68..5d83694d50b 100644
--- a/tests/functional/test_completion.py
+++ b/tests/functional/test_completion.py
@@ -94,7 +94,7 @@ def script_with_launchers(
     tmpdir = tmpdir_factory.mktemp("script_with_launchers")
     script = script_factory(tmpdir.joinpath("workspace"))
     # Re-install pip so we get the launchers.
-    script.pip_install_local("-f", common_wheels, pip_src)
+    script.pip("install", "--no-index", "-f", common_wheels, pip_src)
     return script
 
 
diff --git a/tests/functional/test_config_settings.py b/tests/functional/test_config_settings.py
index 87de5fcc4c7..d762737ea55 100644
--- a/tests/functional/test_config_settings.py
+++ b/tests/functional/test_config_settings.py
@@ -111,27 +111,6 @@ def make_project(
     return name, version, project_dir
 
 
-def test_config_settings_implies_pep517(
-    script: PipTestEnvironment, tmp_path: Path
-) -> None:
-    """Test that setup.py bdist_wheel is not used when config settings are."""
-    pkg_path = tmp_path / "pkga"
-    pkg_path.mkdir()
-    pkg_path.joinpath("setup.py").write_text(
-        "from setuptools import setup; setup(name='pkga')\n"
-    )
-    result = script.pip(
-        "wheel",
-        "--no-build-isolation",
-        "--config-settings",
-        "FOO=Hello",
-        pkg_path,
-        cwd=tmp_path,
-    )
-    assert "Successfully built pkga" in result.stdout
-    assert "Preparing metadata (pyproject.toml)" in result.stdout
-
-
 def test_backend_sees_config(script: PipTestEnvironment) -> None:
     name, version, project_dir = make_project(script.scratch_path)
     script.pip(
diff --git a/tests/functional/test_download.py b/tests/functional/test_download.py
index c5887aa1bf0..3bc9a241ea4 100644
--- a/tests/functional/test_download.py
+++ b/tests/functional/test_download.py
@@ -17,7 +17,6 @@
     ScriptFactory,
     TestData,
     TestPipResult,
-    create_basic_sdist_for_package,
     create_really_basic_wheel,
 )
 from tests.lib.server import MockServer, file_response
@@ -54,8 +53,18 @@ def test_download_wheel(script: PipTestEnvironment, data: TestData) -> None:
     """
     Test using "pip download" to download a *.whl archive.
     """
+    # This test needs --no-build-isolation because `meta` depends on `simple`
+    # which is a source distribution for which it needs to prepare metadata
+    # to look for transitive dependencies.
     result = script.pip(
-        "download", "--no-index", "-f", data.packages, "-d", ".", "meta"
+        "download",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.packages,
+        "-d",
+        ".",
+        "meta",
     )
     result.did_create(Path("scratch") / "meta-1.0-py2.py3-none-any.whl")
     result.did_not_create(script.site_packages / "piptestpackage")
@@ -122,7 +131,14 @@ def test_download_should_download_wheel_deps(
     dep_filename = "translationstring-1.1.tar.gz"
     wheel_path = "/".join((data.find_links, wheel_filename))
     result = script.pip(
-        "download", wheel_path, "-d", ".", "--find-links", data.find_links, "--no-index"
+        "download",
+        "--no-build-isolation",
+        wheel_path,
+        "-d",
+        ".",
+        "--find-links",
+        data.find_links,
+        "--no-index",
     )
     result.did_create(Path("scratch") / wheel_filename)
     result.did_create(Path("scratch") / dep_filename)
@@ -687,8 +703,7 @@ def make_args(python_version: str) -> list[str]:
     args = make_args("33")
     result = script.pip(*args, expect_error=True)
     expected_err = (
-        "ERROR: Package 'mypackage' requires a different Python: "
-        "3.3.0 not in '==3.2'"
+        "ERROR: Package 'mypackage' requires a different Python: 3.3.0 not in '==3.2'"
     )
     assert expected_err in result.stderr, f"stderr: {result.stderr}"
 
@@ -978,6 +993,7 @@ def test_download_prefer_binary_when_wheel_doesnt_satisfy_req(
 
     result = script.pip(
         "download",
+        "--no-build-isolation",
         "--prefer-binary",
         "--no-index",
         "-f",
@@ -1006,6 +1022,7 @@ def test_prefer_binary_when_wheel_doesnt_satisfy_req_req_file(
 
     result = script.pip(
         "download",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.packages,
@@ -1023,6 +1040,7 @@ def test_download_prefer_binary_when_only_tarball_exists(
 ) -> None:
     result = script.pip(
         "download",
+        "--no-build-isolation",
         "--prefer-binary",
         "--no-index",
         "-f",
@@ -1047,6 +1065,7 @@ def test_prefer_binary_when_only_tarball_exists_req_file(
     )
     result = script.pip(
         "download",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.packages,
@@ -1078,6 +1097,7 @@ def test_download_file_url(
 
     shared_script.pip(
         "download",
+        "--no-build-isolation",
         "-d",
         str(download_dir),
         "--no-index",
@@ -1102,7 +1122,12 @@ def test_download_file_url_existing_ok_download(
     url = f"{simple_pkg.as_uri()}#sha256={sha256(downloaded_path_bytes).hexdigest()}"
 
     shared_script.pip(
-        "download", "-d", str(download_dir), url, "--disable-pip-version-check"
+        "download",
+        "--no-build-isolation",
+        "-d",
+        str(download_dir),
+        url,
+        "--disable-pip-version-check",
     )
 
     assert downloaded_path_bytes == downloaded_path.read_bytes()
@@ -1123,6 +1148,7 @@ def test_download_file_url_existing_bad_download(
 
     result = shared_script.pip(
         "download",
+        "--no-build-isolation",
         "-d",
         str(download_dir),
         url,
@@ -1159,6 +1185,7 @@ def test_download_http_url_bad_hash(
 
     result = shared_script.pip(
         "download",
+        "--no-build-isolation",
         "-d",
         str(download_dir),
         url,
@@ -1187,56 +1214,19 @@ def test_download_editable(
     requirements_path.write_text("-e " + editable_path + "\n")
     download_dir = tmpdir / "download_dir"
     script.pip(
-        "download", "--no-deps", "-r", str(requirements_path), "-d", str(download_dir)
+        "download",
+        "--no-build-isolation",
+        "--no-deps",
+        "-r",
+        str(requirements_path),
+        "-d",
+        str(download_dir),
     )
     downloads = os.listdir(download_dir)
     assert len(downloads) == 1
     assert downloads[0].endswith(".zip")
 
 
-def test_download_use_pep517_propagation(
-    script: PipTestEnvironment, tmpdir: Path, common_wheels: Path
-) -> None:
-    """
-    Check that --use-pep517 applies not just to the requirements specified
-    on the command line, but to their dependencies too.
-    """
-
-    create_basic_sdist_for_package(script, "fake_proj", "1.0", depends=["fake_dep"])
-
-    # If --use-pep517 is in effect, then setup.py should be running in an isolated
-    # environment that doesn't have pip in it.
-    create_basic_sdist_for_package(
-        script,
-        "fake_dep",
-        "1.0",
-        setup_py_prelude=textwrap.dedent(
-            """\
-            try:
-                import pip
-            except ImportError:
-                pass
-            else:
-                raise Exception(f"not running in isolation")
-            """
-        ),
-    )
-
-    download_dir = tmpdir / "download_dir"
-    script.pip(
-        "download",
-        f"--dest={download_dir}",
-        "--no-index",
-        f"--find-links={common_wheels}",
-        f"--find-links={script.scratch_path}",
-        "--use-pep517",
-        "fake_proj",
-    )
-
-    downloads = os.listdir(download_dir)
-    assert len(downloads) == 2
-
-
 @pytest.fixture
 def download_local_html_index(
     script: PipTestEnvironment,
@@ -1256,6 +1246,7 @@ def run_for_generated_index(
         """
         pip_args = [
             "download",
+            "--no-build-isolation",
             "-d",
             str(download_dir),
             "-i",
@@ -1287,6 +1278,7 @@ def run_for_generated_index(
         """
         pip_args = [
             "download",
+            "--no-build-isolation",
             "-d",
             str(download_dir),
             "-i",
diff --git a/tests/functional/test_freeze.py b/tests/functional/test_freeze.py
index 9883beb87fd..374c960514c 100644
--- a/tests/functional/test_freeze.py
+++ b/tests/functional/test_freeze.py
@@ -24,7 +24,6 @@
     need_svn,
     wheel,
 )
-from tests.lib.direct_url import get_created_direct_url_path
 from tests.lib.venv import VirtualEnvironment
 
 distribute_re = re.compile("^distribute==[0-9.]+\n", re.MULTILINE)
@@ -210,7 +209,7 @@ def test_freeze_editable_not_vcs(script: PipTestEnvironment) -> None:
     # Rename the .git directory so the directory is no longer recognized
     # as a VCS directory.
     os.rename(os.path.join(pkg_path, ".git"), os.path.join(pkg_path, ".bak"))
-    script.pip("install", "-e", pkg_path)
+    script.pip("install", "--no-build-isolation", "-e", pkg_path)
     result = script.pip("freeze")
 
     # We need to apply os.path.normcase() to the path since that is what
@@ -232,7 +231,7 @@ def test_freeze_editable_git_with_no_remote(
     Test an editable Git install with no remote url.
     """
     pkg_path = _create_test_package(script.scratch_path)
-    script.pip("install", "-e", pkg_path)
+    script.pip("install", "--no-build-isolation", "-e", pkg_path)
     result = script.pip("freeze")
 
     if not deprecated_python:
@@ -596,7 +595,7 @@ def test_freeze_nested_vcs(
         os.fspath(src_path),
         expect_stderr=True,
     )
-    script.pip("install", "-e", src_path, expect_stderr=True)
+    script.pip("install", "--no-build-isolation", "-e", src_path, expect_stderr=True)
 
     # Check the freeze output recognizes the inner VCS.
     result = script.pip("freeze", expect_stderr=True)
@@ -994,7 +993,7 @@ def test_freeze_direct_url_archive(
     script: PipTestEnvironment, shared_data: TestData
 ) -> None:
     req = "simple @ " + shared_data.packages.joinpath("simple-2.0.tar.gz").as_uri()
-    script.pip("install", req)
+    script.pip("install", "--no-build-isolation", req)
     result = script.pip("freeze")
     assert req in result.stdout
 
@@ -1038,8 +1037,8 @@ def test_freeze_pep610_editable(script: PipTestEnvironment) -> None:
     is correctly frozeon as editable.
     """
     pkg_path = _create_test_package(script.scratch_path, name="testpkg")
-    result = script.pip("install", pkg_path)
-    direct_url_path = get_created_direct_url_path(result, "testpkg")
+    result = script.pip("install", "--no-build-isolation", pkg_path)
+    direct_url_path = result.get_created_direct_url_path("testpkg")
     assert direct_url_path
     # patch direct_url.json to simulate an editable install
     with open(direct_url_path) as f:
diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index a1bd81d31d0..3b949baa6a6 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -16,6 +16,7 @@
 import pytest
 
 from pip._internal.cli.status_codes import ERROR, SUCCESS
+from pip._internal.models.direct_url import DirectUrl
 from pip._internal.models.index import PyPI, TestPyPI
 from pip._internal.utils.misc import rmtree
 from pip._internal.utils.urls import path_to_url
@@ -105,8 +106,13 @@ def test_pep518_refuses_conflicting_requires(
     create_basic_wheel_for_package(script, "setuptools", "1.0")
     create_basic_wheel_for_package(script, "wheel", "1.0")
     project_dir = data.src.joinpath("pep518_conflicting_requires")
-    result = script.pip_install_local(
-        "-f", script.scratch_path, project_dir, expect_error=True
+    result = script.pip(
+        "install",
+        "--no-index",
+        "-f",
+        script.scratch_path,
+        project_dir,
+        expect_error=True,
     )
     assert result.returncode != 0
     assert (
@@ -290,7 +296,7 @@ def test_pip_second_command_line_interface_works(
     Check if ``pip<PYVERSION>`` commands behaves equally
     """
     # Re-install pip so we get the launchers.
-    script.pip_install_local("-f", common_wheels, pip_src)
+    script.pip("install", "--no-index", "-f", common_wheels, pip_src)
     args = [f"pip{pyversion}"]
     args.extend(["install", "INITools==0.2"])
     args.extend(["-f", os.fspath(data.packages)])
@@ -400,7 +406,9 @@ def test_basic_install_editable_from_svn(script: PipTestEnvironment) -> None:
     """
     checkout_path = _create_test_package(script.scratch_path)
     repo_url = _create_svn_repo(script.scratch_path, checkout_path)
-    result = script.pip("install", "-e", "svn+" + repo_url + "#egg=version-pkg")
+    result = script.pip(
+        "install", "--no-build-isolation", "-e", "svn+" + repo_url + "#egg=version-pkg"
+    )
     result.assert_installed("version_pkg", with_files=[".svn"])
 
 
@@ -409,6 +417,7 @@ def _test_install_editable_from_git(script: PipTestEnvironment) -> None:
     pkg_path = _create_test_package(script.scratch_path, name="testpackage", vcs="git")
     args = [
         "install",
+        "--no-build-isolation",
         "-e",
         f"git+{pkg_path.as_uri()}#egg=testpackage",
     ]
@@ -437,7 +446,9 @@ def test_install_editable_uninstalls_existing(
     to_install = data.packages.joinpath("pip_test_package-0.1.tar.gz")
     result = script.pip_install_local(to_install)
     assert "Successfully installed pip-test-package" in result.stdout
-    result.assert_installed("piptestpackage", editable=False)
+    result.assert_installed(
+        "piptestpackage", dist_name="pip-test-package", editable=False
+    )
 
     result = script.pip(
         "install",
@@ -449,7 +460,9 @@ def test_install_editable_uninstalls_existing(
             )
         ),
     )
-    result.assert_installed("pip-test-package", with_files=[".git"])
+    result.assert_installed(
+        "piptestpackage", dist_name="pip-test-package", with_files=[".git"]
+    )
     assert "Found existing installation: pip-test-package 0.1" in result.stdout
     assert "Uninstalling pip-test-package-" in result.stdout
     assert "Successfully uninstalled pip-test-package" in result.stdout
@@ -469,13 +482,8 @@ def test_install_editable_uninstalls_existing_from_path(
     result.assert_installed("simplewheel", editable=False)
     result.did_create(simple_folder)
 
-    result = script.pip(
-        "install",
-        "-e",
-        to_install,
-    )
-    install_path = script.site_packages / "simplewheel.egg-link"
-    result.did_create(install_path)
+    result = script.pip_install_local("-e", to_install)
+    script.assert_installed_editable("simplewheel")
     assert "Found existing installation: simplewheel 1.0" in result.stdout
     assert "Uninstalling simplewheel-" in result.stdout
     assert "Successfully uninstalled simplewheel" in result.stdout
@@ -488,7 +496,7 @@ def test_basic_install_editable_from_hg(script: PipTestEnvironment) -> None:
     pkg_path = _create_test_package(script.scratch_path, name="testpackage", vcs="hg")
     url = f"hg+{pkg_path.as_uri()}#egg=testpackage"
     assert url.startswith("hg+file")
-    args = ["install", "-e", url]
+    args = ["install", "--no-build-isolation", "-e", url]
     result = script.pip(*args)
     result.assert_installed("testpackage", with_files=[".hg"])
 
@@ -501,6 +509,7 @@ def test_vcs_url_final_slash_normalization(script: PipTestEnvironment) -> None:
     pkg_path = _create_test_package(script.scratch_path, name="testpackage", vcs="hg")
     args = [
         "install",
+        "--no-build-isolation",
         "-e",
         f"hg+{pkg_path.as_uri()}/#egg=testpackage",
     ]
@@ -516,6 +525,7 @@ def test_install_editable_from_bazaar(script: PipTestEnvironment) -> None:
     )
     args = [
         "install",
+        "--no-build-isolation",
         "-e",
         f"bzr+{pkg_path.as_uri()}/#egg=testpackage",
     ]
@@ -531,7 +541,7 @@ def test_vcs_url_urlquote_normalization(script: PipTestEnvironment) -> None:
         script.scratch_path, name="django_wikiapp", vcs="git"
     )
     url = f"git+{pkg_path.as_uri().replace('django_', 'django%5F')}/#egg=django_wikiapp"
-    script.pip("install", "-e", url)
+    script.pip("install", "--no-build-isolation", "-e", url)
 
 
 @pytest.mark.parametrize("resolver", ["", "--use-deprecated=legacy-resolver"])
@@ -541,7 +551,7 @@ def test_basic_install_from_local_directory(
     """
     Test installing from a local directory.
     """
-    args = ["install"]
+    args = ["install", "--no-build-isolation"]
     if resolver:
         args.append(resolver)
     to_install = data.packages.joinpath("FSPkg")
@@ -571,7 +581,6 @@ def test_basic_install_relative_directory(
     Test installing a requirement using a relative path.
     """
     dist_info_folder = script.site_packages / "fspkg-0.1.dev0.dist-info"
-    egg_link_file = script.site_packages / "FSPkg.egg-link"
     package_folder = script.site_packages / "fspkg"
 
     # Compute relative install path to FSPkg from scratch path.
@@ -589,13 +598,19 @@ def test_basic_install_relative_directory(
 
     # Install as either editable or not.
     if not editable:
-        result = script.pip("install", req_path, cwd=script.scratch_path)
+        result = script.pip(
+            "install", "--no-build-isolation", req_path, cwd=script.scratch_path
+        )
         result.did_create(dist_info_folder)
         result.did_create(package_folder)
     else:
         # Editable install.
-        result = script.pip("install", "-e", req_path, cwd=script.scratch_path)
-        result.did_create(egg_link_file)
+        result = script.pip(
+            "install", "--no-build-isolation", "-e", req_path, cwd=script.scratch_path
+        )
+        direct_url = result.get_created_direct_url("fspkg")
+        assert direct_url
+        assert direct_url.is_local_editable()
 
 
 def test_install_quiet(script: PipTestEnvironment, data: TestData) -> None:
@@ -607,7 +622,7 @@ def test_install_quiet(script: PipTestEnvironment, data: TestData) -> None:
     #   https://github.com/pypa/pip/issues/3418
     #   https://github.com/docker-library/python/issues/83
     to_install = data.packages.joinpath("FSPkg")
-    result = script.pip("install", "-qqq", to_install)
+    result = script.pip("install", "--no-build-isolation", "-qqq", to_install)
     assert result.stdout == ""
     assert result.stderr == ""
 
@@ -789,12 +804,12 @@ def test_hashed_install_from_cache(
         tmpdir,
     ) as reqs_file:
         result = script.pip_install_local(
-            "--use-pep517", "--no-build-isolation", "-r", reqs_file.resolve()
+            "--no-build-isolation", "-r", reqs_file.resolve()
         )
         assert "Created wheel for simple2" in result.stdout
         script.pip("uninstall", "simple2", "-y")
         result = script.pip_install_local(
-            "--use-pep517", "--no-build-isolation", "-r", reqs_file.resolve()
+            "--no-build-isolation", "-r", reqs_file.resolve()
         )
         assert "Using cached simple2" in result.stdout
     # now try with an invalid hash
@@ -804,7 +819,6 @@ def test_hashed_install_from_cache(
     ) as reqs_file:
         script.pip("uninstall", "simple2", "-y")
         result = script.pip_install_local(
-            "--use-pep517",
             "--no-build-isolation",
             "-r",
             reqs_file.resolve(),
@@ -862,7 +876,7 @@ def test_install_from_local_directory_with_in_tree_build(
 
     in_tree_build_dir = to_install / "build"
     assert not in_tree_build_dir.exists()
-    result = script.pip("install", to_install)
+    result = script.pip("install", "--no-build-isolation", to_install)
     fspkg_folder = script.site_packages / "fspkg"
     dist_info_folder = script.site_packages / "fspkg-0.1.dev0.dist-info"
     result.did_create(fspkg_folder)
@@ -895,41 +909,6 @@ def test_editable_install__local_dir_no_setup_py(
     )
 
 
-@pytest.mark.skipif(
-    sys.version_info >= (3, 12),
-    reason="Setuptools<64 does not support Python 3.12+",
-)
-@pytest.mark.network
-def test_editable_install_legacy__local_dir_no_setup_py_with_pyproject(
-    script: PipTestEnvironment,
-) -> None:
-    """
-    Test installing in legacy editable mode from a local directory with no
-    setup.py but that does have pyproject.toml with a build backend that does
-    not support the build_editable hook.
-    """
-    local_dir = script.scratch_path.joinpath("temp")
-    local_dir.mkdir()
-    pyproject_path = local_dir.joinpath("pyproject.toml")
-    pyproject_path.write_text(
-        textwrap.dedent(
-            """
-                [build-system]
-                requires = ["setuptools<64"]
-                build-backend = "setuptools.build_meta"
-            """
-        )
-    )
-
-    result = script.pip("install", "-e", local_dir, expect_error=True)
-    assert not result.files_created
-
-    msg = result.stderr
-    assert "has a 'pyproject.toml'" in msg
-    assert "does not have a 'setup.py' nor a 'setup.cfg'" in msg
-    assert "cannot be installed in editable mode" in msg
-
-
 def test_editable_install__local_dir_setup_requires_with_pyproject(
     script: PipTestEnvironment, shared_data: TestData
 ) -> None:
@@ -1016,7 +995,7 @@ def test_install_curdir(script: PipTestEnvironment, data: TestData) -> None:
     egg_info = join(run_from, "FSPkg.egg-info")
     if os.path.isdir(egg_info):
         rmtree(egg_info)
-    result = script.pip("install", curdir, cwd=run_from)
+    result = script.pip("install", "--no-build-isolation", curdir, cwd=run_from)
     fspkg_folder = script.site_packages / "fspkg"
     dist_info_folder = script.site_packages / "fspkg-0.1.dev0.dist-info"
     result.did_create(fspkg_folder)
@@ -1028,31 +1007,13 @@ def test_install_pardir(script: PipTestEnvironment, data: TestData) -> None:
     Test installing parent directory ('..').
     """
     run_from = data.packages.joinpath("FSPkg", "fspkg")
-    result = script.pip("install", pardir, cwd=run_from)
+    result = script.pip("install", "--no-build-isolation", pardir, cwd=run_from)
     fspkg_folder = script.site_packages / "fspkg"
     dist_info_folder = script.site_packages / "fspkg-0.1.dev0.dist-info"
     result.did_create(fspkg_folder)
     result.did_create(dist_info_folder)
 
 
-@pytest.mark.network
-def test_install_global_option(script: PipTestEnvironment) -> None:
-    """
-    Test using global distutils options.
-    (In particular those that disable the actual install action)
-    """
-    result = script.pip(
-        "install",
-        "--global-option=--version",
-        "INITools==0.1",
-        expect_error=True,  # build is going to fail because of --version
-    )
-    assert "INITools==0.1\n" in result.stdout
-    assert not result.files_created
-    assert "Implying --no-binary=:all:" in result.stderr
-    assert "A possible replacement is to use --config-settings" in result.stderr
-
-
 def test_install_with_hacked_egg_info(
     script: PipTestEnvironment, data: TestData
 ) -> None:
@@ -1060,30 +1021,10 @@ def test_install_with_hacked_egg_info(
     test installing a package which defines its own egg_info class
     """
     run_from = data.packages.joinpath("HackedEggInfo")
-    result = script.pip("install", ".", cwd=run_from)
+    result = script.pip("install", "--no-build-isolation", ".", cwd=run_from)
     assert "Successfully installed hackedegginfo-0.0.0\n" in result.stdout
 
 
-@pytest.mark.xfail
-@pytest.mark.network
-@need_mercurial
-def test_install_global_option_using_editable(
-    script: PipTestEnvironment, tmpdir: Path
-) -> None:
-    """
-    Test using global distutils options, but in an editable installation
-    """
-    url = "hg+http://bitbucket.org/runeh/anyjson"
-    result = script.pip(
-        "install",
-        "--global-option=--version",
-        "-e",
-        f"{local_checkout(url, tmpdir)}@0.2.5#egg=anyjson",
-        expect_stderr=True,
-    )
-    assert "Successfully installed anyjson" in result.stdout
-
-
 @pytest.mark.network
 def test_install_package_with_same_name_in_curdir(script: PipTestEnvironment) -> None:
     """
@@ -1110,7 +1051,7 @@ def test_install_folder_using_dot_slash(script: PipTestEnvironment) -> None:
     script.scratch_path.joinpath("mock").mkdir()
     pkg_path = script.scratch_path / "mock"
     pkg_path.joinpath("setup.py").write_text(mock100_setup_py)
-    result = script.pip("install", "./mock")
+    result = script.pip("install", "--no-build-isolation", "./mock")
     dist_info_folder = script.site_packages / "mock-100.1.dist-info"
     result.did_create(dist_info_folder)
 
@@ -1122,7 +1063,7 @@ def test_install_folder_using_slash_in_the_end(script: PipTestEnvironment) -> No
     script.scratch_path.joinpath("mock").mkdir()
     pkg_path = script.scratch_path / "mock"
     pkg_path.joinpath("setup.py").write_text(mock100_setup_py)
-    result = script.pip("install", "mock" + os.path.sep)
+    result = script.pip("install", "--no-build-isolation", "mock" + os.path.sep)
     dist_info_folder = script.site_packages / "mock-100.1.dist-info"
     result.did_create(dist_info_folder)
 
@@ -1135,7 +1076,7 @@ def test_install_folder_using_relative_path(script: PipTestEnvironment) -> None:
     script.scratch_path.joinpath("initools", "mock").mkdir()
     pkg_path = script.scratch_path / "initools" / "mock"
     pkg_path.joinpath("setup.py").write_text(mock100_setup_py)
-    result = script.pip("install", Path("initools") / "mock")
+    result = script.pip("install", "--no-build-isolation", Path("initools") / "mock")
     dist_info_folder = script.site_packages / "mock-100.1.dist-info"
     result.did_create(dist_info_folder)
 
@@ -1315,7 +1256,7 @@ def main(): pass
     """
         )
     )
-    result = script.pip("install", opt, target_dir, pkga_path)
+    result = script.pip("install", "--no-build-isolation", opt, target_dir, pkga_path)
     # This assertion isn't actually needed, if we get the script warning
     # the script.pip() call will fail with "stderr not expected". But we
     # leave the assertion to make the intention of the code clearer.
@@ -1329,6 +1270,7 @@ def test_install_package_with_root(script: PipTestEnvironment, data: TestData) -
     root_dir = script.scratch_path / "root"
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--root",
         root_dir,
         "-f",
@@ -1360,6 +1302,7 @@ def test_install_package_with_prefix(
     prefix_path = script.scratch_path / "prefix"
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--prefix",
         prefix_path,
         "-f",
@@ -1402,10 +1345,19 @@ def _test_install_editable_with_prefix(
 
     # install pkga package into the absolute prefix directory
     prefix_path = script.scratch_path / "prefix"
-    result = script.pip("install", "--editable", pkga_path, "--prefix", prefix_path)
+    result = script.pip(
+        "install",
+        "--no-build-isolation",
+        "--editable",
+        pkga_path,
+        "--prefix",
+        prefix_path,
+    )
 
     # assert pkga is installed at correct location
-    install_path = script.scratch / site_packages / "pkga.egg-link"
+    install_path = (
+        script.scratch / site_packages / "pkga-0.1.dist-info" / "direct_url.json"
+    )
     result.did_create(install_path)
 
     return result
@@ -1431,7 +1383,11 @@ def test_install_editable_with_target(script: PipTestEnvironment) -> None:
     target.mkdir()
     result = script.pip("install", "--editable", pkg_path, "--target", target)
 
-    result.did_create(script.scratch / "target" / "pkg.egg-link")
+    direct_url_path = result.get_created_direct_url_path("pkg")
+    assert direct_url_path
+    assert direct_url_path.parent.parent == target
+    direct_url = DirectUrl.from_json(direct_url_path.read_text())
+    assert direct_url.is_local_editable()
     result.did_create(script.scratch / "target" / "watching_testrunner.py")
 
 
@@ -1443,28 +1399,6 @@ def test_install_editable_with_prefix_setup_py(script: PipTestEnvironment) -> No
     _test_install_editable_with_prefix(script, {"setup.py": setup_py})
 
 
-@pytest.mark.skipif(
-    sys.version_info >= (3, 12),
-    reason="Setuptools<64 does not support Python 3.12+",
-)
-@pytest.mark.network
-def test_install_editable_legacy_with_prefix_setup_cfg(
-    script: PipTestEnvironment,
-) -> None:
-    setup_cfg = """[metadata]
-name = pkga
-version = 0.1
-"""
-    pyproject_toml = """[build-system]
-requires = ["setuptools<64", "wheel"]
-build-backend = "setuptools.build_meta"
-"""
-    result = _test_install_editable_with_prefix(
-        script, {"setup.cfg": setup_cfg, "pyproject.toml": pyproject_toml}
-    )
-    assert "(setup.py develop) is deprecated" in result.stderr
-
-
 def test_install_package_conflict_prefix_and_user(
     script: PipTestEnvironment, data: TestData
 ) -> None:
@@ -1498,6 +1432,7 @@ def test_install_package_that_emits_unicode(
     to_install = data.packages.joinpath("BrokenEmitsUTF8")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         to_install,
         expect_error=True,
         expect_temp=True,
@@ -1515,7 +1450,7 @@ def test_install_package_with_utf8_setup(
 ) -> None:
     """Install a package with a setup.py that declares a utf-8 encoding."""
     to_install = data.packages.joinpath("SetupPyUTF8")
-    script.pip("install", to_install)
+    script.pip("install", "--no-build-isolation", to_install)
 
 
 def test_install_package_with_latin1_setup(
@@ -1523,7 +1458,7 @@ def test_install_package_with_latin1_setup(
 ) -> None:
     """Install a package with a setup.py that declares a latin-1 encoding."""
     to_install = data.packages.joinpath("SetupPyLatin1")
-    script.pip("install", to_install)
+    script.pip("install", "--no-build-isolation", to_install)
 
 
 def test_url_req_case_mismatch_no_index(
@@ -1539,7 +1474,13 @@ def test_url_req_case_mismatch_no_index(
     """
     Upper = "/".join((data.find_links, "Upper-1.0.tar.gz"))
     result = script.pip(
-        "install", "--no-index", "-f", data.find_links, Upper, "requiresupper"
+        "install",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        Upper,
+        "requiresupper",
     )
 
     # only Upper-1.0.tar.gz should get installed.
@@ -1568,7 +1509,12 @@ def test_url_req_case_mismatch_file_index(
     """
     Dinner = "/".join((data.find_links3, "dinner", "Dinner-1.0.tar.gz"))
     result = script.pip(
-        "install", "--index-url", data.find_links3, Dinner, "requiredinner"
+        "install",
+        "--no-build-isolation",
+        "--index-url",
+        data.find_links3,
+        Dinner,
+        "requiredinner",
     )
 
     # only Dinner-1.0.tar.gz should get installed.
@@ -1588,6 +1534,7 @@ def test_url_incorrect_case_no_index(
     """
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -1611,6 +1558,7 @@ def test_url_incorrect_case_file_index(
     """
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--index-url",
         data.find_links3,
         "dinner",
@@ -1678,7 +1626,7 @@ def test_install_upgrade_editable_depending_on_other_editable(
     """
         )
     )
-    script.pip("install", "--editable", pkga_path)
+    script.pip("install", "--no-build-isolation", "--editable", pkga_path)
     result = script.pip("list", "--format=freeze")
     assert "pkga==0.1" in result.stdout
 
@@ -1694,7 +1642,14 @@ def test_install_upgrade_editable_depending_on_other_editable(
     """
         )
     )
-    script.pip("install", "--upgrade", "--editable", pkgb_path, "--no-index")
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "--upgrade",
+        "--editable",
+        pkgb_path,
+        "--no-index",
+    )
     result = script.pip("list", "--format=freeze")
     assert "pkgb==0.1" in result.stdout
 
@@ -1702,7 +1657,12 @@ def test_install_upgrade_editable_depending_on_other_editable(
 def test_install_subprocess_output_handling(
     script: PipTestEnvironment, data: TestData
 ) -> None:
-    args = ["install", os.fspath(data.src.joinpath("chattymodule"))]
+    args = [
+        "install",
+        "--no-build-isolation",
+        "--no-cache",
+        os.fspath(data.src.joinpath("chattymodule")),
+    ]
 
     # Regular install should not show output from the chatty setup.py
     result = script.pip(*args)
@@ -1713,48 +1673,56 @@ def test_install_subprocess_output_handling(
     # Only count examples with sys.argv[1] == egg_info, because we call
     # setup.py multiple times, which should not count as duplicate output.
     result = script.pip(*(args + ["--verbose"]), expect_stderr=True)
-    assert 1 == result.stderr.count("HELLO FROM CHATTYMODULE egg_info")
+    assert 1 == result.stderr.count(
+        "HELLO FROM CHATTYMODULE prepare_metadata_for_build_wheel"
+    )
+    assert 1 == result.stderr.count("HELLO FROM CHATTYMODULE build_wheel")
     script.pip("uninstall", "-y", "chattymodule")
 
     # If the install fails, then we *should* show the output... but only once,
     # even if --verbose is given.
-    result = script.pip(*(args + ["--global-option=--fail"]), expect_error=True)
-    # This error is emitted 3 times:
-    # - by setup.py bdist_wheel
-    # - by setup.py clean
-    assert 2 == result.stderr.count("I DIE, I DIE")
+    result = script.pip(*(args + ["--config-setting=fail=1"]), expect_error=True)
+    assert 1 == result.stderr.count("I DIE, I DIE")
+    assert 1 == result.stderr.count("I DIE, I DIE in prepare_metadata_for_build_wheel")
 
     result = script.pip(
-        *(args + ["--global-option=--fail", "--verbose"]), expect_error=True
+        *(args + ["--config-setting=fail=1", "--verbose"]), expect_error=True
     )
-    assert 2 == result.stderr.count("I DIE, I DIE")
+    assert 1 == result.stderr.count("I DIE, I DIE")
+    assert 1 == result.stderr.count("I DIE, I DIE in prepare_metadata_for_build_wheel")
 
 
 def test_install_log(script: PipTestEnvironment, data: TestData, tmpdir: Path) -> None:
     # test that verbose logs go to "--log" file
     f = tmpdir.joinpath("log.txt")
-    result = script.pip(f"--log={f}", "install", data.src.joinpath("chattymodule"))
+    result = script.pip(
+        f"--log={f}",
+        "install",
+        "--no-build-isolation",
+        data.src.joinpath("chattymodule"),
+    )
     assert 0 == result.stdout.count("HELLO FROM CHATTYMODULE")
     with open(f) as fp:
-        # one from egg_info, one from install
+        # one from prepare_metadata_for_build_wheel, one from build_wheel
         assert 2 == fp.read().count("HELLO FROM CHATTYMODULE")
 
 
 def test_install_topological_sort(script: PipTestEnvironment, data: TestData) -> None:
-    res = str(script.pip("install", "TopoRequires4", "--no-index", "-f", data.packages))
+    res = str(
+        script.pip(
+            "install",
+            "--no-build-isolation",
+            "TopoRequires4",
+            "--no-index",
+            "-f",
+            data.packages,
+        )
+    )
     order1 = "TopoRequires, TopoRequires2, TopoRequires3, TopoRequires4"
     order2 = "TopoRequires, TopoRequires3, TopoRequires2, TopoRequires4"
     assert order1 in res or order2 in res, res
 
 
-def test_cleanup_after_failed_wheel(script: PipTestEnvironment) -> None:
-    res = script.pip_install_local("wheelbrokenafter", expect_error=True)
-    assert "ERROR: Failed building wheel for wheelbrokenafter" in res.stderr
-    # OK, assert that we *said* we were cleaning up:
-    # /!\ if in need to change this, also change test_pep517_no_legacy_cleanup
-    assert "Running setup.py clean for wheelbrokenafter" in str(res), str(res)
-
-
 def test_install_builds_wheels(script: PipTestEnvironment, data: TestData) -> None:
     # We need to use a subprocess to get the right value on Windows.
     res = script.run(
@@ -1772,6 +1740,7 @@ def test_install_builds_wheels(script: PipTestEnvironment, data: TestData) -> No
     to_install = data.packages.joinpath("requires_wheelbroken_upper")
     res = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -1801,6 +1770,7 @@ def test_install_no_binary_builds_wheels(
     to_install = data.packages.joinpath("requires_wheelbroken_upper")
     res = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "--no-binary=upper",
         "-f",
@@ -1847,10 +1817,13 @@ def test_install_no_binary_uses_cached_wheels(
     script: PipTestEnvironment, data: TestData
 ) -> None:
     # Seed the cache
-    script.pip("install", "--no-index", "-f", data.find_links, "upper")
+    script.pip(
+        "install", "--no-build-isolation", "--no-index", "-f", data.find_links, "upper"
+    )
     script.pip("uninstall", "upper", "-y")
     res = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "--no-binary=:all:",
         "-f",
@@ -1879,6 +1852,7 @@ def test_install_editable_with_wrong_egg_name(
     )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--editable",
         path_to_url(str(pkga_path)) + "#egg=pkgb",
         expect_error=(resolver_variant == "resolvelib"),
@@ -1899,7 +1873,9 @@ def test_install_tar_xz(script: PipTestEnvironment, data: TestData) -> None:
         import lzma  # noqa
     except ImportError:
         pytest.skip("No lzma support")
-    res = script.pip("install", data.packages / "singlemodule-0.0.1.tar.xz")
+    res = script.pip(
+        "install", "--no-build-isolation", data.packages / "singlemodule-0.0.1.tar.xz"
+    )
     assert "Successfully installed singlemodule-0.0.1" in res.stdout, res
 
 
@@ -1908,7 +1884,9 @@ def test_install_tar_lzma(script: PipTestEnvironment, data: TestData) -> None:
         import lzma  # noqa
     except ImportError:
         pytest.skip("No lzma support")
-    res = script.pip("install", data.packages / "singlemodule-0.0.1.tar.lzma")
+    res = script.pip(
+        "install", "--no-build-isolation", data.packages / "singlemodule-0.0.1.tar.lzma"
+    )
     assert "Successfully installed singlemodule-0.0.1" in res.stdout, res
 
 
@@ -1959,7 +1937,7 @@ def test_install_incompatible_python_requires(script: PipTestEnvironment) -> Non
     """
         )
     )
-    result = script.pip("install", pkga_path, expect_error=True)
+    result = script.pip("install", "--no-build-isolation", pkga_path, expect_error=True)
     assert _get_expected_error_text() in result.stderr, str(result)
 
 
@@ -1978,7 +1956,9 @@ def test_install_incompatible_python_requires_editable(
     """
         )
     )
-    result = script.pip("install", f"--editable={pkga_path}", expect_error=True)
+    result = script.pip(
+        "install", "--no-build-isolation", f"--editable={pkga_path}", expect_error=True
+    )
     assert _get_expected_error_text() in result.stderr, str(result)
 
 
@@ -2021,7 +2001,7 @@ def test_install_compatible_python_requires(script: PipTestEnvironment) -> None:
     """
         )
     )
-    res = script.pip("install", pkga_path)
+    res = script.pip("install", "--no-build-isolation", pkga_path)
     assert "Successfully installed pkga-0.1" in res.stdout, res
 
 
@@ -2064,6 +2044,7 @@ def test_install_from_test_pypi_with_ext_url_dep_is_blocked(
 ) -> None:
     res = script.pip(
         "install",
+        "--no-build-isolation",
         "--index-url",
         index,
         "pep-508-url-deps",
@@ -2127,12 +2108,15 @@ def test_install_conflict_results_in_warning(
     )
 
     # Install pkgA without its dependency
-    result1 = script.pip("install", "--no-index", pkgA_path, "--no-deps")
+    result1 = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkgA_path, "--no-deps"
+    )
     assert "Successfully installed pkgA-1.0" in result1.stdout, str(result1)
 
     # Then install an incorrect version of the dependency
     result2 = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         pkgB_path,
         allow_stderr_error=True,
@@ -2157,11 +2141,19 @@ def test_install_conflict_warning_can_be_suppressed(
     )
 
     # Install pkgA without its dependency
-    result1 = script.pip("install", "--no-index", pkgA_path, "--no-deps")
+    result1 = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkgA_path, "--no-deps"
+    )
     assert "Successfully installed pkgA-1.0" in result1.stdout, str(result1)
 
     # Then install an incorrect version of the dependency; suppressing warning
-    result2 = script.pip("install", "--no-index", pkgB_path, "--no-warn-conflicts")
+    result2 = script.pip(
+        "install",
+        "--no-build-isolation",
+        "--no-index",
+        pkgB_path,
+        "--no-warn-conflicts",
+    )
     assert "Successfully installed pkgB-2.0" in result2.stdout, str(result2)
 
 
@@ -2237,6 +2229,7 @@ def test_ignore_yanked_file(script: PipTestEnvironment, data: TestData) -> None:
     result = script.pip(
         "install",
         "simple",
+        "--no-build-isolation",
         "--index-url",
         data.index_url("yanked"),
     )
@@ -2272,7 +2265,13 @@ def test_valid_index_url_argument(
     Test the behaviour of an valid --index-url argument
     """
 
-    result = script.pip("install", "--index-url", shared_data.find_links3, "Dinner")
+    result = script.pip(
+        "install",
+        "--no-build-isolation",
+        "--index-url",
+        shared_data.find_links3,
+        "Dinner",
+    )
 
     assert "Successfully installed Dinner" in result.stdout, str(result)
 
@@ -2289,6 +2288,7 @@ def test_install_yanked_file_and_print_warning(
     result = script.pip(
         "install",
         "simple==3.0",
+        "--no-build-isolation",
         "--index-url",
         data.index_url("yanked"),
         expect_stderr=True,
@@ -2377,7 +2377,15 @@ def test_install_sends_client_cert(
 
     url = f"https://{server.host}:{server.port}/simple"
 
-    args = ["install", "-vvv", "--cert", cert_path, "--client-cert", cert_path]
+    args = [
+        "install",
+        "--no-build-isolation",
+        "-vvv",
+        "--cert",
+        cert_path,
+        "--client-cert",
+        cert_path,
+    ]
     args.extend(["--index-url", url])
     args.extend(install_args)
     args.append("simple")
@@ -2469,7 +2477,9 @@ def test_install_verify_package_name_normalization(
     pkg_path = create_test_package_with_setup(
         script, name="simple-package", version="1.0"
     )
-    result = script.pip("install", "-e", ".", expect_stderr=True, cwd=pkg_path)
+    result = script.pip(
+        "install", "--no-build-isolation", "-e", ".", expect_stderr=True, cwd=pkg_path
+    )
     assert "Successfully installed simple-package" in result.stdout
 
     result = script.pip("install", package_name)
@@ -2480,7 +2490,7 @@ def test_install_logs_pip_version_in_debug(
     script: PipTestEnvironment, shared_data: TestData
 ) -> None:
     fake_package = shared_data.packages / "simple-2.0.tar.gz"
-    result = script.pip("install", "-v", fake_package)
+    result = script.pip("install", "--no-build-isolation", "-v", fake_package)
     pattern = "Using pip .* from .*"
     assert_re_match(pattern, result.stdout)
 
@@ -2504,6 +2514,7 @@ def install_find_links(
             else ()
         ),
         *(("--dry-run",) if dry_run else ()),
+        "--no-build-isolation",
         "--no-index",
         "--find-links",
         data.find_links,
diff --git a/tests/functional/test_install_check.py b/tests/functional/test_install_check.py
index a0598fe2703..cb8312b535d 100644
--- a/tests/functional/test_install_check.py
+++ b/tests/functional/test_install_check.py
@@ -27,13 +27,16 @@ def test_check_install_canonicalization(script: PipTestEnvironment) -> None:
     )
 
     # Let's install pkgA without its dependency
-    result = script.pip("install", "--no-index", pkga_path, "--no-deps")
+    result = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkga_path, "--no-deps"
+    )
     assert "Successfully installed pkgA-1.0" in result.stdout, str(result)
 
     # Install the first missing dependency. Only an error for the
     # second dependency should remain.
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         normal_path,
         "--quiet",
@@ -51,6 +54,7 @@ def test_check_install_canonicalization(script: PipTestEnvironment) -> None:
     # name normalization (as in https://github.com/pypa/pip/issues/5134)
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         special_path,
         "--quiet",
@@ -88,12 +92,15 @@ def test_check_install_does_not_warn_for_out_of_graph_issues(
     )
 
     # Install a package without it's dependencies
-    result = script.pip("install", "--no-index", pkg_broken_path, "--no-deps")
+    result = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkg_broken_path, "--no-deps"
+    )
     assert "requires" not in result.stderr
 
     # Install conflict package
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         pkg_conflict_path,
         allow_stderr_error=True,
@@ -110,6 +117,7 @@ def test_check_install_does_not_warn_for_out_of_graph_issues(
     # Install unrelated package
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         pkg_unrelated_path,
         "--quiet",
diff --git a/tests/functional/test_install_cleanup.py b/tests/functional/test_install_cleanup.py
index bc34defc978..457657073c4 100644
--- a/tests/functional/test_install_cleanup.py
+++ b/tests/functional/test_install_cleanup.py
@@ -28,16 +28,3 @@ def test_no_clean_option_blocks_cleaning_after_install(
         allow_stderr_warning=True,
     )
     assert exists(build)
-
-
-@pytest.mark.network
-def test_pep517_no_legacy_cleanup(script: PipTestEnvironment, data: TestData) -> None:
-    """Test a PEP 517 failed build does not attempt a legacy cleanup"""
-    to_install = data.packages.joinpath("pep517_wrapper_buildsys")
-    script.environ["PIP_TEST_FAIL_BUILD_WHEEL"] = "1"
-    res = script.pip("install", "-f", data.find_links, to_install, expect_error=True)
-    # Must not have built the package
-    expected = "Failed building wheel for pep517-wrapper-buildsys"
-    assert expected in str(res)
-    # Must not have attempted legacy cleanup
-    assert "setup.py clean" not in str(res)
diff --git a/tests/functional/test_install_compat.py b/tests/functional/test_install_compat.py
index 47ba41bdf9e..c0ba64c25d7 100644
--- a/tests/functional/test_install_compat.py
+++ b/tests/functional/test_install_compat.py
@@ -73,4 +73,4 @@ def test_setup_py_with_dos_line_endings(
     Refs https://github.com/pypa/pip/issues/237
     """
     to_install = data.packages.joinpath("LineEndings")
-    script.pip("install", to_install)
+    script.pip("install", "--no-build-isolation", to_install)
diff --git a/tests/functional/test_install_config.py b/tests/functional/test_install_config.py
index baee7e80d55..678e51822c1 100644
--- a/tests/functional/test_install_config.py
+++ b/tests/functional/test_install_config.py
@@ -199,6 +199,7 @@ def test_config_file_override_stack(
     script.pip("install", "-vvv", "INITools", expect_error=True)
     script.pip(
         "install",
+        "--no-build-isolation",
         "-vvv",
         "--index-url",
         f"{base_address}/simple3",
@@ -250,7 +251,13 @@ def test_install_no_binary_via_config_disables_cached_wheels(
         )
         config_file.close()
         res = script.pip(
-            "install", "--no-index", "-f", data.find_links, "upper", expect_stderr=True
+            "install",
+            "--no-build-isolation",
+            "--no-index",
+            "-f",
+            data.find_links,
+            "upper",
+            expect_stderr=True,
         )
     finally:
         os.unlink(config_file.name)
@@ -520,6 +527,7 @@ def set_password(self, url, username):
     with server_running(server):
         result = script.pip(
             "install",
+            "--no-build-isolation",
             "--index-url",
             url,
             "--cert",
diff --git a/tests/functional/test_install_direct_url.py b/tests/functional/test_install_direct_url.py
index 5aefab09cb3..f67a8615b21 100644
--- a/tests/functional/test_install_direct_url.py
+++ b/tests/functional/test_install_direct_url.py
@@ -3,29 +3,19 @@
 from pip._internal.models.direct_url import VcsInfo
 
 from tests.lib import PipTestEnvironment, TestData, _create_test_package
-from tests.lib.direct_url import get_created_direct_url
 
 
 def test_install_find_links_no_direct_url(script: PipTestEnvironment) -> None:
     result = script.pip_install_local("simple")
-    assert not get_created_direct_url(result, "simple")
-
-
-def test_install_vcs_editable_no_direct_url(script: PipTestEnvironment) -> None:
-    pkg_path = _create_test_package(script.scratch_path, name="testpkg")
-    args = ["install", "-e", f"git+{pkg_path.as_uri()}#egg=testpkg"]
-    result = script.pip(*args)
-    # legacy editable installs do not generate .dist-info,
-    # hence no direct_url.json
-    assert not get_created_direct_url(result, "testpkg")
+    assert not result.get_created_direct_url("simple")
 
 
 def test_install_vcs_non_editable_direct_url(script: PipTestEnvironment) -> None:
     pkg_path = _create_test_package(script.scratch_path, name="testpkg")
     url = pkg_path.as_uri()
-    args = ["install", f"git+{url}#egg=testpkg"]
+    args = ["install", "--no-build-isolation", f"git+{url}#egg=testpkg"]
     result = script.pip(*args)
-    direct_url = get_created_direct_url(result, "testpkg")
+    direct_url = result.get_created_direct_url("testpkg")
     assert direct_url
     assert direct_url.url == url
     assert isinstance(direct_url.info, VcsInfo)
@@ -35,8 +25,8 @@ def test_install_vcs_non_editable_direct_url(script: PipTestEnvironment) -> None
 def test_install_archive_direct_url(script: PipTestEnvironment, data: TestData) -> None:
     req = "simple @ " + data.packages.joinpath("simple-2.0.tar.gz").as_uri()
     assert req.startswith("simple @ file://")
-    result = script.pip("install", req)
-    assert get_created_direct_url(result, "simple")
+    result = script.pip("install", "--no-build-isolation", req)
+    assert result.get_created_direct_url("simple")
 
 
 @pytest.mark.network
@@ -48,7 +38,7 @@ def test_install_vcs_constraint_direct_url(script: PipTestEnvironment) -> None:
         "#egg=pip-test-package"
     )
     result = script.pip("install", "pip-test-package", "-c", constraints_file)
-    assert get_created_direct_url(result, "pip_test_package")
+    assert result.get_created_direct_url("pip_test_package")
 
 
 def test_install_vcs_constraint_direct_file_url(script: PipTestEnvironment) -> None:
@@ -56,5 +46,7 @@ def test_install_vcs_constraint_direct_file_url(script: PipTestEnvironment) -> N
     url = pkg_path.as_uri()
     constraints_file = script.scratch_path / "constraints.txt"
     constraints_file.write_text(f"git+{url}#egg=testpkg")
-    result = script.pip("install", "testpkg", "-c", constraints_file)
-    assert get_created_direct_url(result, "testpkg")
+    result = script.pip(
+        "install", "--no-build-isolation", "testpkg", "-c", constraints_file
+    )
+    assert result.get_created_direct_url("testpkg")
diff --git a/tests/functional/test_install_extras.py b/tests/functional/test_install_extras.py
index 44dbc2a3694..5a0ebc23ced 100644
--- a/tests/functional/test_install_extras.py
+++ b/tests/functional/test_install_extras.py
@@ -35,6 +35,7 @@ def test_extras_after_wheel(script: PipTestEnvironment, data: TestData) -> None:
 
     no_extra = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -45,6 +46,7 @@ def test_extras_after_wheel(script: PipTestEnvironment, data: TestData) -> None:
 
     extra = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -84,6 +86,7 @@ def test_nonexistent_extra_warns_user_no_wheel(
     result = script.pip(
         "install",
         "--no-binary=:all:",
+        "--no-build-isolation",
         "--no-index",
         "--find-links=" + data.find_links,
         "simple[nonexistent]",
@@ -273,4 +276,4 @@ def test_install_setuptools_extras_inconsistency(
             """
         )
     )
-    script.pip("install", "--dry-run", test_project_path)
+    script.pip("install", "--no-build-isolation", "--dry-run", test_project_path)
diff --git a/tests/functional/test_install_index.py b/tests/functional/test_install_index.py
index 73b122a6141..4ebc005ba09 100644
--- a/tests/functional/test_install_index.py
+++ b/tests/functional/test_install_index.py
@@ -9,6 +9,7 @@ def test_find_links_relative_path(script: PipTestEnvironment, data: TestData) ->
     result = script.pip(
         "install",
         "parent==0.1",
+        "--no-build-isolation",
         "--no-index",
         "--find-links",
         "packages/",
@@ -27,7 +28,6 @@ def test_find_links_no_doctype(script: PipTestEnvironment, data: TestData) -> No
     result = script.pip(
         "install",
         "simple==1.0",
-        "--use-pep517",
         "--no-build-isolation",
         "--no-index",
         "--find-links",
@@ -52,6 +52,7 @@ def test_find_links_requirements_file_relative_path(
     )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "-r",
         script.scratch_path / "test-req.txt",
         cwd=data.root,
@@ -69,7 +70,9 @@ def test_install_from_file_index_hash_link(
     Test that a pkg can be installed from a file:// index using a link with a
     hash
     """
-    result = script.pip("install", "-i", data.index_url(), "simple==1.0")
+    result = script.pip(
+        "install", "--no-build-isolation", "-i", data.index_url(), "simple==1.0"
+    )
     dist_info_folder = script.site_packages / "simple-1.0.dist-info"
     result.did_create(dist_info_folder)
 
@@ -79,6 +82,8 @@ def test_file_index_url_quoting(script: PipTestEnvironment, data: TestData) -> N
     Test url quoting of file index url with a space
     """
     index_url = data.index_url("in dex")
-    result = script.pip("install", "-vvv", "--index-url", index_url, "simple")
+    result = script.pip(
+        "install", "--no-build-isolation", "-vvv", "--index-url", index_url, "simple"
+    )
     result.did_create(script.site_packages / "simple")
     result.did_create(script.site_packages / "simple-1.0.dist-info")
diff --git a/tests/functional/test_install_report.py b/tests/functional/test_install_report.py
index 968e30f2dec..ab35c30932b 100644
--- a/tests/functional/test_install_report.py
+++ b/tests/functional/test_install_report.py
@@ -50,6 +50,7 @@ def test_install_report_dep(
     report_path = tmp_path / "report.json"
     script.pip(
         "install",
+        "--no-build-isolation",
         "require_simple",
         "--dry-run",
         "--no-index",
@@ -75,6 +76,7 @@ def test_yanked_version(
     report_path = tmp_path / "report.json"
     script.pip(
         "install",
+        "--no-build-isolation",
         "simple==3.0",
         "--index-url",
         data.index_url("yanked"),
@@ -102,6 +104,7 @@ def test_skipped_yanked_version(
     report_path = tmp_path / "report.json"
     script.pip(
         "install",
+        "--no-build-isolation",
         "simple",
         "--index-url",
         data.index_url("yanked"),
diff --git a/tests/functional/test_install_reqs.py b/tests/functional/test_install_reqs.py
index 3c5b6db4a68..e1c0906298f 100644
--- a/tests/functional/test_install_reqs.py
+++ b/tests/functional/test_install_reqs.py
@@ -13,7 +13,6 @@
     _create_test_package_with_subdirectory,
     create_basic_sdist_for_package,
     create_basic_wheel_for_package,
-    make_wheel,
     need_svn,
     requirements_file,
 )
@@ -188,8 +187,7 @@ def test_schema_check_in_requirements_file(script: PipTestEnvironment) -> None:
     """
     script.scratch_path.joinpath("file-egg-req.txt").write_text(
         "\n{}\n".format(
-            "git://github.com/alex/django-fixture-generator.git"
-            "#egg=fixture_generator"
+            "git://github.com/alex/django-fixture-generator.git#egg=fixture_generator"
         )
     )
 
@@ -217,7 +215,6 @@ def test_relative_requirements_file(
 
     """
     dist_info_folder = script.site_packages / "fspkg-0.1.dev0.dist-info"
-    egg_link_file = script.site_packages / "FSPkg.egg-link"
     package_folder = script.site_packages / "fspkg"
 
     # Compute relative install path to FSPkg from scratch path.
@@ -238,7 +235,12 @@ def test_relative_requirements_file(
     if not editable:
         with requirements_file(req_path + "\n", script.scratch_path) as reqs_file:
             result = script.pip(
-                "install", "-vvv", "-r", reqs_file.name, cwd=script.scratch_path
+                "install",
+                "--no-build-isolation",
+                "-vvv",
+                "-r",
+                reqs_file.name,
+                cwd=script.scratch_path,
             )
             result.did_create(dist_info_folder)
             result.did_create(package_folder)
@@ -247,9 +249,16 @@ def test_relative_requirements_file(
             "-e " + req_path + "\n", script.scratch_path
         ) as reqs_file:
             result = script.pip(
-                "install", "-vvv", "-r", reqs_file.name, cwd=script.scratch_path
+                "install",
+                "--no-build-isolation",
+                "-vvv",
+                "-r",
+                reqs_file.name,
+                cwd=script.scratch_path,
             )
-            result.did_create(egg_link_file)
+            direct_url = result.get_created_direct_url("fspkg")
+            assert direct_url
+            assert direct_url.is_local_editable()
 
 
 @pytest.mark.xfail
@@ -290,6 +299,7 @@ def test_package_in_constraints_and_dependencies(
     )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -315,6 +325,7 @@ def test_constraints_apply_to_dependency_groups(
     )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -331,6 +342,7 @@ def test_multiple_constraints_files(script: PipTestEnvironment, data: TestData)
     script.scratch_path.joinpath("inner.txt").write_text("Upper==1.0")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -357,6 +369,7 @@ def test_respect_order_in_requirements_file(
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -384,9 +397,8 @@ def test_install_local_editable_with_extras(
     res = script.pip_install_local(
         "-e", f"{to_install}[bar]", allow_stderr_warning=True
     )
-    res.did_update(script.site_packages / "easy-install.pth")
-    res.did_create(script.site_packages / "LocalExtras.egg-link")
-    res.did_create(script.site_packages / "simple")
+    res.assert_installed("LocalExtras", editable=True, editable_vcs=False)
+    res.assert_installed("simple", editable=False)
 
 
 def test_install_collected_dependencies_first(script: PipTestEnvironment) -> None:
@@ -444,7 +456,13 @@ def test_wheel_user_with_prefix_in_pydistutils_cfg(
         )
 
     result = script.pip(
-        "install", "--user", "--no-index", "-f", data.find_links, "requiresupper"
+        "install",
+        "--no-build-isolation",
+        "--user",
+        "--no-index",
+        "-f",
+        data.find_links,
+        "requiresupper",
     )
     # Check that we are really installing a wheel
     assert "installed requiresupper" in result.stdout
@@ -456,6 +474,7 @@ def test_constraints_not_installed_by_default(
     script.scratch_path.joinpath("c.txt").write_text("requiresupper")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -491,6 +510,7 @@ def test_constraints_local_editable_install_causes_error(
     to_install = data.src.joinpath("singlemodule")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -523,6 +543,7 @@ def test_constraints_local_install_causes_error(
     to_install = data.src.joinpath("singlemodule")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -570,6 +591,7 @@ def test_constraints_constrain_to_local(
     )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -589,6 +611,7 @@ def test_constrained_to_url_install_same_url(
     script.scratch_path.joinpath("constraints.txt").write_text(constraints)
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -817,8 +840,7 @@ def test_install_unsupported_wheel_link_with_marker(script: PipTestEnvironment)
     result = script.pip("install", "-r", script.scratch_path / "with-marker.txt")
 
     assert (
-        "Ignoring asdf: markers 'sys_platform == \"xyz\"' don't match "
-        "your environment"
+        "Ignoring asdf: markers 'sys_platform == \"xyz\"' don't match your environment"
     ) in result.stdout
     assert len(result.files_created) == 0
 
@@ -918,26 +940,3 @@ def test_config_settings_local_to_package(
     assert "--verbose" not in simple3_args
     simple2_args = simple2_sdist.args()
     assert "--verbose" not in simple2_args
-
-
-def test_nonpep517_setuptools_import_failure(script: PipTestEnvironment) -> None:
-    """Any import failures of `setuptools` should inform the user both that it's
-    not pip's fault, but also exactly what went wrong in the import."""
-    # Install a poisoned version of 'setuptools' that fails to import.
-    name = "setuptools_poisoned"
-    module = """\
-raise ImportError("this 'setuptools' was intentionally poisoned")
-"""
-    path = make_wheel(name, "0.1.0", extra_files={"setuptools.py": module}).save_to_dir(
-        script.scratch_path
-    )
-    script.pip("install", "--no-index", path)
-
-    result = script.pip_install_local("--no-use-pep517", "simple", expect_error=True)
-    nice_message = (
-        "ERROR: Can not execute `setup.py`"
-        " since setuptools failed to import in the build environment"
-    )
-    exc_message = "ImportError: this 'setuptools' was intentionally poisoned"
-    assert nice_message in result.stderr
-    assert exc_message in result.stderr
diff --git a/tests/functional/test_install_requested.py b/tests/functional/test_install_requested.py
index 2c5cad9fcc8..cc834af2ab2 100644
--- a/tests/functional/test_install_requested.py
+++ b/tests/functional/test_install_requested.py
@@ -23,7 +23,12 @@ def _assert_requested_absent(
 
 def test_install_requested_basic(script: PipTestEnvironment, data: TestData) -> None:
     result = script.pip(
-        "install", "--no-index", "-f", data.find_links, "require_simple"
+        "install",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        "require_simple",
     )
     _assert_requested_present(script, result, "require_simple", "1.0")
     # dependency is not REQUESTED
@@ -36,6 +41,7 @@ def test_install_requested_requirements(
     script.scratch_path.joinpath("requirements.txt").write_text("require_simple\n")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -54,6 +60,7 @@ def test_install_requested_dep_in_requirements(
     )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -72,6 +79,7 @@ def test_install_requested_reqs_and_constraints(
     script.scratch_path.joinpath("constraints.txt").write_text("simple<3\n")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -94,6 +102,7 @@ def test_install_requested_in_reqs_and_constraints(
     script.scratch_path.joinpath("constraints.txt").write_text("simple<3\n")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -113,6 +122,7 @@ def test_install_requested_from_cli_with_constraint(
     script.scratch_path.joinpath("constraints.txt").write_text("simple<3\n")
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -133,6 +143,7 @@ def test_install_requested_from_cli_with_url_constraint(
     )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "-c",
         script.scratch_path / "constraints.txt",
diff --git a/tests/functional/test_install_upgrade.py b/tests/functional/test_install_upgrade.py
index 43b43d64f82..de52218e96f 100644
--- a/tests/functional/test_install_upgrade.py
+++ b/tests/functional/test_install_upgrade.py
@@ -167,9 +167,22 @@ def test_upgrade_with_newest_already_installed(
     If the newest version of a package is already installed, the package should
     not be reinstalled and the user should be informed.
     """
-    script.pip("install", "-f", data.find_links, "--no-index", "simple")
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "simple",
+    )
     result = script.pip(
-        "install", "--upgrade", "-f", data.find_links, "--no-index", "simple"
+        "install",
+        "--no-build-isolation",
+        "--upgrade",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "simple",
     )
     assert not result.files_created, "simple upgraded when it should not have"
     if resolver_variant == "resolvelib":
@@ -217,8 +230,7 @@ def test_uninstall_before_upgrade_from_url(script: PipTestEnvironment) -> None:
     result.did_create(script.site_packages / "initools")
     result2 = script.pip(
         "install",
-        "https://files.pythonhosted.org/packages/source/I/INITools/INITools-"
-        "0.3.tar.gz",
+        "https://files.pythonhosted.org/packages/source/I/INITools/INITools-0.3.tar.gz",
     )
     assert result2.files_created, "upgrade to INITools 0.3 failed"
     result3 = script.pip("uninstall", "initools", "-y")
@@ -236,8 +248,7 @@ def test_upgrade_to_same_version_from_url(script: PipTestEnvironment) -> None:
     result.did_create(script.site_packages / "initools")
     result2 = script.pip(
         "install",
-        "https://files.pythonhosted.org/packages/source/I/INITools/INITools-"
-        "0.3.tar.gz",
+        "https://files.pythonhosted.org/packages/source/I/INITools/INITools-0.3.tar.gz",
     )
     assert (
         script.site_packages / "initools" not in result2.files_updated
@@ -288,10 +299,18 @@ def test_uninstall_rollback(script: PipTestEnvironment, data: TestData) -> None:
     crafted to fail on install).
 
     """
-    result = script.pip("install", "-f", data.find_links, "--no-index", "broken==0.1")
+    result = script.pip(
+        "install",
+        "--no-build-isolation",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "broken==0.1",
+    )
     result.did_create(script.site_packages / "broken.py")
     result2 = script.pip(
         "install",
+        "--no-build-isolation",
         "-f",
         data.find_links,
         "--no-index",
diff --git a/tests/functional/test_install_user.py b/tests/functional/test_install_user.py
index 0b1e025cbbe..7d39bc3ce11 100644
--- a/tests/functional/test_install_user.py
+++ b/tests/functional/test_install_user.py
@@ -75,7 +75,7 @@ def test_install_subversion_usersite_editable_with_distribute(
                 )
             ),
         )
-        result.assert_installed("INITools", use_user_site=True)
+        result.assert_installed("INITools")
 
     def test_install_from_current_directory_into_usersite(
         self, script: PipTestEnvironment, data: TestData
@@ -86,6 +86,7 @@ def test_install_from_current_directory_into_usersite(
         run_from = data.packages.joinpath("FSPkg")
         result = script.pip(
             "install",
+            "--no-build-isolation",
             "-vvv",
             "--user",
             curdir,
diff --git a/tests/functional/test_install_vcs_git.py b/tests/functional/test_install_vcs_git.py
index 38d416fb62d..187b6faafa0 100644
--- a/tests/functional/test_install_vcs_git.py
+++ b/tests/functional/test_install_vcs_git.py
@@ -108,7 +108,11 @@ def _install_version_pkg_only(
     """
     version_pkg_url = _make_version_pkg_url(path, rev=rev)
     script.pip(
-        "install", "-e", version_pkg_url, allow_stderr_warning=allow_stderr_warning
+        "install",
+        "--no-build-isolation",
+        "-e",
+        version_pkg_url,
+        allow_stderr_warning=allow_stderr_warning,
     )
 
 
@@ -183,7 +187,9 @@ def test_install_editable_from_git_with_https(
     url_path = "pypa/pip-test-package.git"
     local_url = _github_checkout(url_path, tmpdir, egg="pip-test-package")
     result = script.pip("install", "-e", local_url)
-    result.assert_installed("pip-test-package", with_files=[".git"])
+    result.assert_installed(
+        "piptestpackage", dist_name="pip-test-package", with_files=[".git"]
+    )
 
 
 @pytest.mark.network
@@ -193,11 +199,12 @@ def test_install_noneditable_git(script: PipTestEnvironment) -> None:
     """
     result = script.pip(
         "install",
-        "git+https://github.com/pypa/pip-test-package.git"
-        "@0.1.1#egg=pip-test-package",
+        "git+https://github.com/pypa/pip-test-package.git@0.1.1#egg=pip-test-package",
     )
     dist_info_folder = script.site_packages / "pip_test_package-0.1.1.dist-info"
-    result.assert_installed("piptestpackage", without_egg_link=True, editable=False)
+    result.assert_installed(
+        "piptestpackage", dist_name="pip-test-package", editable=False
+    )
     result.did_create(dist_info_folder)
 
 
@@ -339,29 +346,6 @@ def test_install_git_logs_commit_sha(
     assert f"Resolved {base_local_url[4:]} to commit {expected_sha}" in result.stdout
 
 
-@pytest.mark.network
-def test_git_with_tag_name_and_update(script: PipTestEnvironment, tmpdir: Path) -> None:
-    """
-    Test cloning a git repository and updating to a different version.
-    """
-    url_path = "pypa/pip-test-package.git"
-    base_local_url = _github_checkout(url_path, tmpdir)
-
-    local_url = f"{base_local_url}#egg=pip-test-package"
-    result = script.pip("install", "-e", local_url)
-    result.assert_installed("pip-test-package", with_files=[".git"])
-
-    new_local_url = f"{base_local_url}@0.1.2#egg=pip-test-package"
-    result = script.pip(
-        "install",
-        "--global-option=--version",
-        "-e",
-        new_local_url,
-        allow_stderr_warning=True,
-    )
-    assert "0.1.2" in result.stdout
-
-
 @pytest.mark.network
 def test_git_branch_should_not_be_changed(
     script: PipTestEnvironment, tmpdir: Path
@@ -393,7 +377,6 @@ def test_git_with_non_editable_unpacking(
     )
     result = script.pip(
         "install",
-        "--global-option=--quiet",
         local_url,
         allow_stderr_warning=True,
     )
@@ -446,7 +429,7 @@ def test_git_with_ambiguous_revs(script: PipTestEnvironment) -> None:
     version_pkg_path = _create_test_package(script.scratch_path)
     version_pkg_url = _make_version_pkg_url(version_pkg_path, rev="0.1")
     script.run("git", "tag", "0.1", cwd=version_pkg_path)
-    result = script.pip("install", "-e", version_pkg_url)
+    result = script.pip("install", "--no-build-isolation", "-e", version_pkg_url)
     assert "Could not find a tag or branch" not in result.stdout
     # it is 'version-pkg' instead of 'version_pkg' because
     # egg-link name is version-pkg.egg-link because it is a single .py module
@@ -587,11 +570,11 @@ def test_install_git_branch_not_cached(script: PipTestEnvironment) -> None:
     PKG = "gitbranchnotcached"
     repo_dir = _create_test_package(script.scratch_path, name=PKG)
     url = _make_version_pkg_url(repo_dir, rev="master", name=PKG)
-    result = script.pip("install", url, "--only-binary=:all:")
+    result = script.pip("install", "--no-build-isolation", url, "--only-binary=:all:")
     assert f"Successfully built {PKG}" in result.stdout, result.stdout
     script.pip("uninstall", "-y", PKG)
     # build occurs on the second install too because it is not cached
-    result = script.pip("install", url)
+    result = script.pip("install", "--no-build-isolation", url)
     assert f"Successfully built {PKG}" in result.stdout, result.stdout
 
 
@@ -603,9 +586,9 @@ def test_install_git_sha_cached(script: PipTestEnvironment) -> None:
     repo_dir = _create_test_package(script.scratch_path, name=PKG)
     commit = script.run("git", "rev-parse", "HEAD", cwd=repo_dir).stdout.strip()
     url = _make_version_pkg_url(repo_dir, rev=commit, name=PKG)
-    result = script.pip("install", url)
+    result = script.pip("install", "--no-build-isolation", url)
     assert f"Successfully built {PKG}" in result.stdout, result.stdout
     script.pip("uninstall", "-y", PKG)
     # build does not occur on the second install because it is cached
-    result = script.pip("install", url)
+    result = script.pip("install", "--no-build-isolation", url)
     assert f"Successfully built {PKG}" not in result.stdout, result.stdout
diff --git a/tests/functional/test_install_wheel.py b/tests/functional/test_install_wheel.py
index e01ecfb57f3..9ab76ba17b7 100644
--- a/tests/functional/test_install_wheel.py
+++ b/tests/functional/test_install_wheel.py
@@ -38,7 +38,7 @@ def test_install_from_future_wheel_version(
 
     result = script.pip("install", package, "--no-index", expect_error=True)
     with pytest.raises(TestFailure):
-        result.assert_installed("futurewheel", without_egg_link=True, editable=False)
+        result.assert_installed("futurewheel", editable=False)
 
     package = make_wheel_with_file(
         name="futurewheel",
@@ -46,7 +46,7 @@ def test_install_from_future_wheel_version(
         wheel_metadata_updates={"Wheel-Version": "1.9"},
     ).save_to_dir(tmpdir)
     result = script.pip("install", package, "--no-index", expect_stderr=True)
-    result.assert_installed("futurewheel", without_egg_link=True, editable=False)
+    result.assert_installed("futurewheel", editable=False)
 
 
 @pytest.mark.parametrize(
@@ -67,7 +67,7 @@ def test_install_from_broken_wheel(
     package = data.packages.joinpath(wheel_name)
     result = script.pip("install", package, "--no-index", expect_error=True)
     with pytest.raises(TestFailure):
-        result.assert_installed("futurewheel", without_egg_link=True, editable=False)
+        result.assert_installed("futurewheel", editable=False)
 
 
 def test_basic_install_from_wheel(
@@ -299,6 +299,7 @@ def test_install_from_wheel_installs_deps(
     shutil.copy(data.packages / "source-1.0.tar.gz", tmpdir)
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-index",
         "--find-links",
         tmpdir,
diff --git a/tests/functional/test_list.py b/tests/functional/test_list.py
index 468e6acd6c2..f058439279f 100644
--- a/tests/functional/test_list.py
+++ b/tests/functional/test_list.py
@@ -15,7 +15,6 @@
     make_wheel,
     wheel,
 )
-from tests.lib.direct_url import get_created_direct_url_path
 
 
 @pytest.fixture(scope="session")
@@ -28,6 +27,7 @@ def simple_script(
     script = script_factory(tmpdir.joinpath("workspace"))
     script.pip(
         "install",
+        "--no-build-isolation",
         "-f",
         shared_data.find_links,
         "--no-index",
@@ -170,6 +170,7 @@ def test_uptodate_flag(script: PipTestEnvironment, data: TestData) -> None:
     """
     script.pip(
         "install",
+        "--no-build-isolation",
         "-f",
         data.find_links,
         "--no-index",
@@ -210,6 +211,7 @@ def test_uptodate_columns_flag(script: PipTestEnvironment, data: TestData) -> No
     """
     script.pip(
         "install",
+        "--no-build-isolation",
         "-f",
         data.find_links,
         "--no-index",
@@ -245,6 +247,7 @@ def test_outdated_flag(script: PipTestEnvironment, data: TestData) -> None:
     """
     script.pip(
         "install",
+        "--no-build-isolation",
         "-f",
         data.find_links,
         "--no-index",
@@ -299,6 +302,7 @@ def test_outdated_columns_flag(script: PipTestEnvironment, data: TestData) -> No
     """
     script.pip(
         "install",
+        "--no-build-isolation",
         "-f",
         data.find_links,
         "--no-index",
@@ -338,9 +342,17 @@ def pip_test_package_script(
 ) -> PipTestEnvironment:
     tmpdir = tmpdir_factory.mktemp("pip_test_package")
     script = script_factory(tmpdir.joinpath("workspace"))
-    script.pip("install", "-f", shared_data.find_links, "--no-index", "simple==1.0")
     script.pip(
         "install",
+        "--no-build-isolation",
+        "-f",
+        shared_data.find_links,
+        "--no-index",
+        "simple==1.0",
+    )
+    script.pip(
+        "install",
+        "--no-build-isolation",
         "-e",
         "git+https://github.com/pypa/pip-test-package.git#egg=pip-test-package",
     )
@@ -427,9 +439,17 @@ def test_outdated_editables_flag(script: PipTestEnvironment, data: TestData) ->
     """
     test the behavior of --editable --outdated flag in the list command
     """
-    script.pip("install", "-f", data.find_links, "--no-index", "simple==1.0")
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "simple==1.0",
+    )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "-e",
         "git+https://github.com/pypa/pip-test-package.git@0.1#egg=pip-test-package",
     )
@@ -452,9 +472,17 @@ def test_outdated_editables_columns_flag(
     """
     test the behavior of --editable --outdated flag in the list command
     """
-    script.pip("install", "-f", data.find_links, "--no-index", "simple==1.0")
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "simple==1.0",
+    )
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "-e",
         "git+https://github.com/pypa/pip-test-package.git@0.1#egg=pip-test-package",
     )
@@ -479,6 +507,7 @@ def test_outdated_not_required_flag(script: PipTestEnvironment, data: TestData)
     """
     script.pip(
         "install",
+        "--no-build-isolation",
         "-f",
         data.find_links,
         "--no-index",
@@ -498,7 +527,14 @@ def test_outdated_not_required_flag(script: PipTestEnvironment, data: TestData)
 
 
 def test_outdated_pre(script: PipTestEnvironment, data: TestData) -> None:
-    script.pip("install", "-f", data.find_links, "--no-index", "simple==1.0")
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "simple==1.0",
+    )
 
     # Let's build a fake wheelhouse
     script.scratch_path.joinpath("wheelhouse").mkdir()
@@ -546,7 +582,14 @@ def test_outdated_pre(script: PipTestEnvironment, data: TestData) -> None:
 
 def test_outdated_formats(script: PipTestEnvironment, data: TestData) -> None:
     """Test of different outdated formats"""
-    script.pip("install", "-f", data.find_links, "--no-index", "simple==1.0")
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "simple==1.0",
+    )
 
     # Let's build a fake wheelhouse
     script.scratch_path.joinpath("wheelhouse").mkdir()
@@ -608,7 +651,14 @@ def test_outdated_formats(script: PipTestEnvironment, data: TestData) -> None:
 
 
 def test_not_required_flag(script: PipTestEnvironment, data: TestData) -> None:
-    script.pip("install", "-f", data.find_links, "--no-index", "TopoRequires4")
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "-f",
+        data.find_links,
+        "--no-index",
+        "TopoRequires4",
+    )
     result = script.pip("list", "--not-required", expect_stderr=True)
     assert "TopoRequires4 " in result.stdout, str(result)
     assert "TopoRequires " not in result.stdout
@@ -735,8 +785,8 @@ def test_list_pep610_editable(script: PipTestEnvironment) -> None:
     is correctly listed as editable.
     """
     pkg_path = _create_test_package(script.scratch_path, name="testpkg")
-    result = script.pip("install", pkg_path)
-    direct_url_path = get_created_direct_url_path(result, "testpkg")
+    result = script.pip("install", "--no-build-isolation", pkg_path)
+    direct_url_path = result.get_created_direct_url_path("testpkg")
     assert direct_url_path
     # patch direct_url.json to simulate an editable install
     with open(direct_url_path) as f:
diff --git a/tests/functional/test_lock.py b/tests/functional/test_lock.py
index 727bd72c8a0..9cc6a03a494 100644
--- a/tests/functional/test_lock.py
+++ b/tests/functional/test_lock.py
@@ -59,6 +59,7 @@ def test_lock_sdist_from_findlinks(
     """Test locking a simple wheel package, to the default pylock.toml."""
     result = script.pip(
         "lock",
+        "--no-build-isolation",
         "simple==2.0",
         "--no-binary=simple",
         "--quiet",
diff --git a/tests/functional/test_new_resolver.py b/tests/functional/test_new_resolver.py
index c094e675a30..b5b26128037 100644
--- a/tests/functional/test_new_resolver.py
+++ b/tests/functional/test_new_resolver.py
@@ -5,7 +5,6 @@
 from typing import TYPE_CHECKING, Callable, Protocol
 
 import pytest
-from packaging.utils import canonicalize_name
 
 from tests.conftest import ScriptFactory
 from tests.lib import (
@@ -14,27 +13,12 @@
     create_basic_wheel_for_package,
     create_test_package_with_setup,
 )
-from tests.lib.direct_url import get_created_direct_url
 from tests.lib.venv import VirtualEnvironment
 from tests.lib.wheel import make_wheel
 
 MakeFakeWheel = Callable[[str, str, str], pathlib.Path]
 
 
-def assert_editable(script: PipTestEnvironment, *args: str) -> None:
-    # This simply checks whether all of the listed packages have a
-    # corresponding .egg-link file installed.
-    # TODO: Implement a more rigorous way to test for editable installations.
-    egg_links = {f"{canonicalize_name(arg)}.egg-link" for arg in args}
-    actual_egg_links = {
-        f"{canonicalize_name(p.stem)}.egg-link"
-        for p in script.site_packages_path.glob("*.egg-link")
-    }
-    assert (
-        egg_links <= actual_egg_links
-    ), f"{args!r} not all found in {script.site_packages_path!r}"
-
-
 @pytest.fixture
 def make_fake_wheel(script: PipTestEnvironment) -> MakeFakeWheel:
     def _make_fake_wheel(name: str, version: str, wheel_tag: str) -> pathlib.Path:
@@ -331,6 +315,7 @@ def test_new_resolver_installs_editable(script: PipTestEnvironment) -> None:
     )
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "--find-links",
@@ -340,7 +325,7 @@ def test_new_resolver_installs_editable(script: PipTestEnvironment) -> None:
         source_dir,
     )
     script.assert_installed(base="0.1.0", dep="0.1.0")
-    assert_editable(script, "dep")
+    script.assert_installed_editable("dep")
 
 
 @pytest.mark.parametrize(
@@ -380,6 +365,7 @@ def test_new_resolver_requires_python(
 
     args = [
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "--find-links",
@@ -536,6 +522,7 @@ def test_new_resolver_only_builds_sdists_when_needed(
     # We only ever need to check dep 0.2.0 as it's the latest version
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "--find-links",
@@ -807,6 +794,7 @@ def test_new_resolver_constraint_on_path_empty(
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "-c",
@@ -1045,6 +1033,7 @@ def test_new_resolver_extra_merge_in_package(
 
         script.pip(
             "install",
+            "--no-build-isolation",
             "--no-cache-dir",
             "--no-index",
             "--find-links",
@@ -1089,6 +1078,7 @@ def test_new_resolver_build_directory_error_zazo_19(script: PipTestEnvironment)
 
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "--find-links",
@@ -1184,6 +1174,7 @@ def test_new_resolver_prefers_installed_in_upgrade_if_latest(
     # Install the version that's not on the index.
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         local_pkg,
@@ -1192,6 +1183,7 @@ def test_new_resolver_prefers_installed_in_upgrade_if_latest(
     # Now --upgrade should still pick the local version because it's "better".
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "--find-links",
@@ -1303,6 +1295,7 @@ def test_new_resolver_does_reinstall_local_sdists(script: PipTestEnvironment) ->
     )
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         archive_path,
@@ -1311,6 +1304,7 @@ def test_new_resolver_does_reinstall_local_sdists(script: PipTestEnvironment) ->
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         archive_path,
@@ -1324,6 +1318,7 @@ def test_new_resolver_does_reinstall_local_paths(script: PipTestEnvironment) ->
     pkg = create_test_package_with_setup(script, name="pkg", version="1.0")
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         pkg,
@@ -1332,6 +1327,7 @@ def test_new_resolver_does_reinstall_local_paths(script: PipTestEnvironment) ->
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         pkg,
@@ -1350,6 +1346,7 @@ def test_new_resolver_does_not_reinstall_when_from_a_local_index(
     )
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "--find-links",
@@ -1863,6 +1860,7 @@ def test_new_resolver_succeeds_on_matching_constraint_and_requirement(
 
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "-c",
@@ -1872,7 +1870,7 @@ def test_new_resolver_succeeds_on_matching_constraint_and_requirement(
 
     script.assert_installed(test_pkg="0.1.0")
     if editable:
-        assert_editable(script, "test_pkg")
+        script.assert_installed_editable("test_pkg")
 
 
 def test_new_resolver_applies_url_constraint_to_dep(script: PipTestEnvironment) -> None:
@@ -2155,9 +2153,9 @@ def test_new_resolver_direct_url_with_extras(
     )
 
     script.assert_installed(pkg1="1", pkg2="1", pkg3="1")
-    assert not get_created_direct_url(result, "pkg1")
-    assert get_created_direct_url(result, "pkg2")
-    assert not get_created_direct_url(result, "pkg3")
+    assert not result.get_created_direct_url("pkg1")
+    assert result.get_created_direct_url("pkg2")
+    assert not result.get_created_direct_url("pkg3")
 
 
 def test_new_resolver_modifies_installed_incompatible(
@@ -2215,6 +2213,7 @@ def test_new_resolver_transitively_depends_on_unnamed_local(
 
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         "--find-links",
@@ -2268,6 +2267,7 @@ def test_new_resolver_file_url_normalize(
 
     script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-index",
         format_input(lib_a),
@@ -2479,7 +2479,7 @@ def test_new_resolver_constraint_on_link_with_extra_indirect(
 def test_new_resolver_do_not_backtrack_on_build_failure(
     script: PipTestEnvironment,
 ) -> None:
-    create_basic_sdist_for_package(script, "pkg1", "2.0", fails_egg_info=True)
+    create_basic_sdist_for_package(script, "pkg1", "2.0", fails_build=True)
     create_basic_wheel_for_package(script, "pkg1", "1.0")
 
     result = script.pip(
@@ -2492,14 +2492,14 @@ def test_new_resolver_do_not_backtrack_on_build_failure(
         expect_error=True,
     )
 
-    assert "egg_info" in result.stderr
+    assert "Failed to build 'pkg1'" in result.stderr
 
 
 def test_new_resolver_works_when_failing_package_builds_are_disallowed(
     script: PipTestEnvironment,
 ) -> None:
     create_basic_wheel_for_package(script, "pkg2", "1.0", depends=["pkg1"])
-    create_basic_sdist_for_package(script, "pkg1", "2.0", fails_egg_info=True)
+    create_basic_sdist_for_package(script, "pkg1", "2.0", fails_build=True)
     create_basic_wheel_for_package(script, "pkg1", "1.0")
     constraints_file = script.scratch_path / "constraints.txt"
     constraints_file.write_text("pkg1 != 2.0")
diff --git a/tests/functional/test_new_resolver_errors.py b/tests/functional/test_new_resolver_errors.py
index ebca917d0a5..06c7dafaf41 100644
--- a/tests/functional/test_new_resolver_errors.py
+++ b/tests/functional/test_new_resolver_errors.py
@@ -88,7 +88,9 @@ def test_new_resolver_requires_python_error(script: PipTestEnvironment) -> None:
     )
 
     # This always fails because pkgb can never be satisfied.
-    result = script.pip("install", "--no-index", pkga, pkgb, expect_error=True)
+    result = script.pip(
+        "install", "--no-build-isolation", "--no-index", pkga, pkgb, expect_error=True
+    )
 
     # The error message should mention the Requires-Python: value causing the
     # conflict, not the compatible one.
diff --git a/tests/functional/test_new_resolver_hashes.py b/tests/functional/test_new_resolver_hashes.py
index 5fb1f2bf799..b9d4d7c4adf 100644
--- a/tests/functional/test_new_resolver_hashes.py
+++ b/tests/functional/test_new_resolver_hashes.py
@@ -72,6 +72,7 @@ def test_new_resolver_hash_intersect(
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-deps",
         "--no-index",
@@ -102,6 +103,7 @@ def test_new_resolver_hash_intersect_from_constraint(
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-deps",
         "--no-index",
@@ -163,6 +165,7 @@ def test_new_resolver_hash_intersect_empty(
 
     result = script.pip(
         "install",
+        "--no-build-isolation",
         "--no-cache-dir",
         "--no-deps",
         "--no-index",
diff --git a/tests/functional/test_pep517.py b/tests/functional/test_pep517.py
index 47dae96817f..e36c5f80277 100644
--- a/tests/functional/test_pep517.py
+++ b/tests/functional/test_pep517.py
@@ -4,7 +4,6 @@
 from pathlib import Path
 from typing import Any
 
-import pytest
 import tomli_w
 
 from pip._internal.build_env import (
@@ -129,25 +128,6 @@ def test_pep517_install_with_reqs(
     result.assert_installed("project", editable=False)
 
 
-def test_no_use_pep517_without_setup_py(
-    script: PipTestEnvironment, tmpdir: Path, data: TestData
-) -> None:
-    """Using --no-use-pep517 requires setup.py"""
-    project_dir = make_project(
-        tmpdir, requires=["test_backend"], backend="test_backend"
-    )
-    result = script.pip(
-        "install",
-        "--no-index",
-        "--no-use-pep517",
-        "-f",
-        data.backends,
-        project_dir,
-        expect_error=True,
-    )
-    assert "project does not have a setup.py" in result.stderr
-
-
 def test_conflicting_pep517_backend_requirements(
     script: PipTestEnvironment, tmpdir: Path, data: TestData
 ) -> None:
@@ -390,45 +370,3 @@ def test_explicit_setuptools_backend(
         project_dir,
     )
     result.assert_installed(name, editable=False)
-
-
-@pytest.mark.network
-def test_pep517_and_build_options(
-    script: PipTestEnvironment, tmpdir: Path, data: TestData, common_wheels: Path
-) -> None:
-    """Backend generated requirements are installed in the build env"""
-    project_dir, name = make_pyproject_with_setup(tmpdir)
-    result = script.pip(
-        "wheel",
-        "--wheel-dir",
-        tmpdir,
-        "--build-option",
-        "foo",
-        "-f",
-        common_wheels,
-        project_dir,
-        allow_stderr_warning=True,
-    )
-    assert "Ignoring --build-option when building" in result.stderr
-    assert "using PEP 517" in result.stderr
-
-
-@pytest.mark.network
-def test_pep517_and_global_options(
-    script: PipTestEnvironment, tmpdir: Path, data: TestData, common_wheels: Path
-) -> None:
-    """Backend generated requirements are installed in the build env"""
-    project_dir, name = make_pyproject_with_setup(tmpdir)
-    result = script.pip(
-        "wheel",
-        "--wheel-dir",
-        tmpdir,
-        "--global-option",
-        "foo",
-        "-f",
-        common_wheels,
-        project_dir,
-        allow_stderr_warning=True,
-    )
-    assert "Ignoring --global-option when building" in result.stderr
-    assert "using PEP 517" in result.stderr
diff --git a/tests/functional/test_pep660.py b/tests/functional/test_pep660.py
index 9cf3da31172..881d0cc8402 100644
--- a/tests/functional/test_pep660.py
+++ b/tests/functional/test_pep660.py
@@ -2,6 +2,7 @@
 from pathlib import Path
 from typing import Any
 
+import pytest
 import tomli_w
 
 from tests.lib import PipTestEnvironment
@@ -164,53 +165,31 @@ def test_install_pep660_from_reqs_file(
     ), "a .egg-link file should not have been created"
 
 
-def test_install_no_pep660_setup_py_fallback(
-    tmpdir: Path, script: PipTestEnvironment
+@pytest.mark.parametrize("isolation_arg", [[], ["--no-build-isolation"]])
+def test_install_no_pep660(
+    isolation_arg: list[str],
+    tmpdir: Path,
+    script: PipTestEnvironment,
+    common_wheels: Path,
 ) -> None:
     """
-    Test that we fall back to setuptools develop when using a backend that
-    does not support build_editable. Since there is a pyproject.toml,
-    the prepare_metadata_for_build_wheel hook is called.
-    """
-    project_dir = _make_project(tmpdir, BACKEND_WITHOUT_PEP660, with_setup_py=True)
-    result = script.pip(
-        "install",
-        "--no-index",
-        "--no-build-isolation",
-        "--editable",
-        project_dir,
-        allow_stderr_warning=False,
-    )
-    _assert_hook_called(project_dir, "prepare_metadata_for_build_wheel")
-    assert (
-        result.test_env.site_packages.joinpath("project.egg-link")
-        in result.files_created
-    ), "a .egg-link file should have been created"
-
+    Test the error message when the build backend does not support PEP 660.
 
-def test_install_no_pep660_setup_cfg_fallback(
-    tmpdir: Path, script: PipTestEnvironment
-) -> None:
-    """
-    Test that we fall back to setuptools develop when using a backend that
-    does not support build_editable. Since there is a pyproject.toml,
-    the prepare_metadata_for_build_wheel hook is called.
+    The error is the same with and without build isolation.
     """
-    project_dir = _make_project(tmpdir, BACKEND_WITHOUT_PEP660, with_setup_py=False)
+    project_dir = _make_project(tmpdir, BACKEND_WITHOUT_PEP660, with_setup_py=True)
     result = script.pip(
         "install",
         "--no-index",
-        "--no-build-isolation",
+        "-f",
+        common_wheels,
+        *isolation_arg,
         "--editable",
         project_dir,
-        allow_stderr_warning=False,
+        allow_error=True,
     )
-    print(result.stdout, result.stderr)
-    _assert_hook_called(project_dir, "prepare_metadata_for_build_wheel")
-    assert (
-        result.test_env.site_packages.joinpath("project.egg-link")
-        in result.files_created
-    ), ".egg-link file should have been created"
+    assert result.returncode != 0
+    assert "missing the 'build_editable' hook" in result.stderr
 
 
 def test_wheel_editable_pep660_basic(tmpdir: Path, script: PipTestEnvironment) -> None:
diff --git a/tests/functional/test_proxy.py b/tests/functional/test_proxy.py
index 32eb94a1edf..0810d82d3af 100644
--- a/tests/functional/test_proxy.py
+++ b/tests/functional/test_proxy.py
@@ -77,6 +77,7 @@ def test_proxy_does_not_override_netrc(
         script.environ["NETRC"] = netrc
         script.pip(
             "install",
+            "--no-build-isolation",
             "--proxy",
             f"http://127.0.0.1:{proxy1.flags.port}",
             "--trusted-host",
diff --git a/tests/functional/test_show.py b/tests/functional/test_show.py
index ea831935372..40a40b0aa24 100644
--- a/tests/functional/test_show.py
+++ b/tests/functional/test_show.py
@@ -36,7 +36,7 @@ def test_show_with_files_not_found(script: PipTestEnvironment, data: TestData) -
     installed-files.txt not found.
     """
     editable = data.packages.joinpath("SetupPyUTF8")
-    script.pip("install", "-e", editable)
+    script.run("python", "setup.py", "develop", cwd=editable)
     result = script.pip("show", "-f", "SetupPyUTF8")
     lines = result.stdout.splitlines()
     assert len(lines) == 13
@@ -264,7 +264,14 @@ def test_pip_show_divider(script: PipTestEnvironment, data: TestData) -> None:
     """
     Expect a divider between packages
     """
-    script.pip("install", "pip-test-package", "--no-index", "-f", data.packages)
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "pip-test-package",
+        "--no-index",
+        "-f",
+        data.packages,
+    )
     result = script.pip("show", "pip", "pip-test-package")
     lines = result.stdout.splitlines()
     assert "---" in lines
@@ -273,7 +280,14 @@ def test_pip_show_divider(script: PipTestEnvironment, data: TestData) -> None:
 def test_package_name_is_canonicalized(
     script: PipTestEnvironment, data: TestData
 ) -> None:
-    script.pip("install", "pip-test-package", "--no-index", "-f", data.packages)
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "pip-test-package",
+        "--no-index",
+        "-f",
+        data.packages,
+    )
 
     dash_show_result = script.pip("show", "pip-test-package")
     underscore_upper_show_result = script.pip("show", "pip-test_Package")
@@ -289,7 +303,14 @@ def test_show_required_by_packages_basic(
     Test that installed packages that depend on this package are shown
     """
     editable_path = os.path.join(data.src, "requires_simple")
-    script.pip("install", "--no-index", "-f", data.find_links, editable_path)
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        editable_path,
+    )
 
     result = script.pip("show", "simple")
     lines = result.stdout.splitlines()
@@ -309,7 +330,14 @@ def test_show_required_by_packages_capitalized(
     where the package has a capital letter
     """
     editable_path = os.path.join(data.src, "requires_capitalized")
-    script.pip("install", "--no-index", "-f", data.find_links, editable_path)
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        editable_path,
+    )
 
     result = script.pip("show", "simple")
     lines = result.stdout.splitlines()
@@ -330,9 +358,23 @@ def test_show_required_by_packages_requiring_capitalized(
     lower and upper case letters
     """
     required_package_path = os.path.join(data.src, "requires_capitalized")
-    script.pip("install", "--no-index", "-f", data.find_links, required_package_path)
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        required_package_path,
+    )
     editable_path = os.path.join(data.src, "requires_requires_capitalized")
-    script.pip("install", "--no-index", "-f", data.find_links, editable_path)
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        editable_path,
+    )
 
     result = script.pip("show", "Requires_Capitalized")
     lines = result.stdout.splitlines()
diff --git a/tests/functional/test_uninstall.py b/tests/functional/test_uninstall.py
index 7d041bb69e0..1b2f32b152c 100644
--- a/tests/functional/test_uninstall.py
+++ b/tests/functional/test_uninstall.py
@@ -210,9 +210,9 @@ def test_uninstall_overlapping_package(
     parent_pkg = data.packages.joinpath("parent-0.1.tar.gz")
     child_pkg = data.packages.joinpath("child-0.1.tar.gz")
 
-    result1 = script.pip("install", parent_pkg)
+    result1 = script.pip("install", "--no-build-isolation", parent_pkg)
     result1.did_create(join(script.site_packages, "parent"))
-    result2 = script.pip("install", child_pkg)
+    result2 = script.pip("install", "--no-build-isolation", child_pkg)
     result2.did_create(join(script.site_packages, "child"))
     result2.did_create(
         normpath(join(script.site_packages, "parent/plugins/child_plugin.py"))
@@ -269,7 +269,7 @@ def test_uninstall_entry_point_colon_in_name(
     script_name = script.bin_path.joinpath(console_scripts.split("=")[0].strip())
     if sys.platform == "win32":
         script_name = script_name.with_suffix(".exe")
-    script.pip("install", pkg_path)
+    script.pip("install", "--no-build-isolation", pkg_path)
     assert script_name.exists()
     script.assert_installed(ep_install="0.1")
 
@@ -296,7 +296,7 @@ def test_uninstall_gui_scripts(script: PipTestEnvironment) -> None:
     script_name = script.bin_path.joinpath("test_")
     if sys.platform == "win32":
         script_name = script_name.with_suffix(".exe")
-    script.pip("install", pkg_path)
+    script.pip("install", "--no-build-isolation", pkg_path)
     assert script_name.exists()
     script.pip("uninstall", pkg_name, "-y")
     assert not script_name.exists()
@@ -313,7 +313,7 @@ def test_uninstall_console_scripts(script: PipTestEnvironment) -> None:
         version="0.1",
         entry_points={"console_scripts": ["discover = discover:main"]},
     )
-    result = script.pip("install", pkg_path)
+    result = script.pip("install", "--no-build-isolation", pkg_path)
     result.did_create(script.bin / f"discover{script.exe}")
     result2 = script.pip("uninstall", "discover", "-y")
     assert_all_changes(
@@ -344,7 +344,7 @@ def test_uninstall_console_scripts_uppercase_name(script: PipTestEnvironment) ->
     )
     script_name = script.bin_path.joinpath("Test" + script.exe)
 
-    script.pip("install", pkg_path)
+    script.pip("install", "--no-build-isolation", pkg_path)
     assert script_name.exists()
 
     script.pip("uninstall", "ep_install", "-y")
@@ -437,7 +437,7 @@ def _test_uninstall_editable_with_source_outside_venv(
         temp_pkg_dir,
         expect_stderr=True,
     )
-    result2 = script.pip("install", "-e", temp_pkg_dir)
+    result2 = script.run("python", "setup.py", "develop", cwd=temp_pkg_dir)
     result2.did_create(join(script.site_packages, "pip-test-package.egg-link"))
     result3 = script.pip("uninstall", "-y", "pip-test-package")
     assert_all_changes(
@@ -665,9 +665,16 @@ def test_uninstall_editable_and_pip_install(
     script.environ["SETUPTOOLS_SYS_PATH_TECHNIQUE"] = "raw"
 
     pkg_path = data.packages.joinpath("FSPkg")
-    script.pip("install", "-e", ".", expect_stderr=True, cwd=pkg_path)
+    script.run("python", "setup.py", "develop", expect_stderr=True, cwd=pkg_path)
     # ensure both are installed with --ignore-installed:
-    script.pip("install", "--ignore-installed", ".", expect_stderr=True, cwd=pkg_path)
+    script.pip(
+        "install",
+        "--no-build-isolation",
+        "--ignore-installed",
+        ".",
+        expect_stderr=True,
+        cwd=pkg_path,
+    )
     script.assert_installed(FSPkg="0.1.dev0")
     # Uninstall both develop and install
     uninstall = script.pip("uninstall", "FSPkg", "-y")
@@ -702,7 +709,7 @@ def test_uninstall_editable_and_pip_install_easy_install_remove(
 
     # Install FSPkg
     pkg_path = data.packages.joinpath("FSPkg")
-    script.pip("install", "-e", ".", expect_stderr=True, cwd=pkg_path)
+    script.run("python", "setup.py", "develop", expect_stderr=True, cwd=pkg_path)
 
     # Rename easy-install.pth to pip-test-fspkg.pth
     easy_install_pth = join(script.site_packages_path, "easy-install.pth")
diff --git a/tests/functional/test_uninstall_user.py b/tests/functional/test_uninstall_user.py
index 63ba5e581d0..25b7512e12c 100644
--- a/tests/functional/test_uninstall_user.py
+++ b/tests/functional/test_uninstall_user.py
@@ -92,7 +92,9 @@ def test_uninstall_editable_from_usersite(
 
         # install
         to_install = data.packages.joinpath("FSPkg")
-        result1 = script.pip("install", "--user", "-e", to_install)
+        result1 = script.run(
+            "python", "setup.py", "develop", "--user", "--prefix=", cwd=to_install
+        )
         egg_link = script.user_site / "FSPkg.egg-link"
         result1.did_create(egg_link)
 
diff --git a/tests/functional/test_wheel.py b/tests/functional/test_wheel.py
index e1ede880496..66099dbebd1 100644
--- a/tests/functional/test_wheel.py
+++ b/tests/functional/test_wheel.py
@@ -53,6 +53,7 @@ def test_pip_wheel_success(script: PipTestEnvironment, data: TestData) -> None:
     """
     result = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -87,6 +88,7 @@ def test_pip_wheel_success_with_dependency_group(
     )
     result = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -111,6 +113,7 @@ def test_pip_wheel_build_cache(script: PipTestEnvironment, data: TestData) -> No
     """
     result = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -162,6 +165,7 @@ def test_pip_wheel_build_relative_cachedir(
     """
     result = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -179,6 +183,7 @@ def test_pip_wheel_builds_when_no_binary_set(
     # Check that the wheel package is ignored
     res = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "--no-binary",
         ":all:",
@@ -199,6 +204,7 @@ def test_pip_wheel_readonly_cache(
     # Check that the wheel package is ignored
     res = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -219,7 +225,13 @@ def test_pip_wheel_builds_editable_deps(
     """
     editable_path = os.path.join(data.src, "requires_simple")
     result = script.pip(
-        "wheel", "--no-index", "-f", data.find_links, "-e", editable_path
+        "wheel",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        "-e",
+        editable_path,
     )
     wheel_file_name = f"simple-1.0-py{pyversion[0]}-none-any.whl"
     wheel_file_path = script.scratch / wheel_file_name
@@ -232,7 +244,13 @@ def test_pip_wheel_builds_editable(script: PipTestEnvironment, data: TestData) -
     """
     editable_path = os.path.join(data.src, "simplewheel-1.0")
     result = script.pip(
-        "wheel", "--no-index", "-f", data.find_links, "-e", editable_path
+        "wheel",
+        "--no-build-isolation",
+        "--no-index",
+        "-f",
+        data.find_links,
+        "-e",
+        editable_path,
     )
     wheel_file_name = f"simplewheel-1.0-py{pyversion[0]}-none-any.whl"
     wheel_file_path = script.scratch / wheel_file_name
@@ -248,6 +266,7 @@ def test_pip_wheel_git_editable_keeps_clone(
     """
     script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-deps",
         "-e",
         "git+https://github.com/pypa/pip-test-package#egg=pip-test-package",
@@ -270,7 +289,15 @@ def test_pip_wheel_builds_editable_does_not_create_zip(
     wheel_dir = tmpdir / "wheel_dir"
     wheel_dir.mkdir()
     editable_path = os.path.join(data.src, "simplewheel-1.0")
-    script.pip("wheel", "--no-deps", "-e", editable_path, "-w", wheel_dir)
+    script.pip(
+        "wheel",
+        "--no-build-isolation",
+        "--no-deps",
+        "-e",
+        editable_path,
+        "-w",
+        wheel_dir,
+    )
     wheels = os.listdir(wheel_dir)
     assert len(wheels) == 1
     assert wheels[0].endswith(".whl")
@@ -282,6 +309,7 @@ def test_pip_wheel_fail(script: PipTestEnvironment, data: TestData) -> None:
     """
     result = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -304,6 +332,7 @@ def test_pip_wheel_source_deps(script: PipTestEnvironment, data: TestData) -> No
     # 'requires_source' is a wheel that depends on the 'source' project
     result = script.pip(
         "wheel",
+        "--no-build-isolation",
         "--no-index",
         "-f",
         data.find_links,
@@ -321,7 +350,7 @@ def test_wheel_package_with_latin1_setup(
     """Create a wheel from a package with latin-1 encoded setup.py."""
 
     pkg_to_wheel = data.packages.joinpath("SetupPyLatin1")
-    result = script.pip("wheel", pkg_to_wheel)
+    result = script.pip("wheel", "--no-build-isolation", pkg_to_wheel)
     assert "Successfully built SetupPyUTF8" in result.stdout
 
 
@@ -419,7 +448,9 @@ def test_legacy_wheels_are_not_confused_with_other_files(
     pkg_to_wheel = data.src / "simplewheel-1.0"
     add_files_to_dist_directory(pkg_to_wheel)
 
-    result = script.pip("wheel", pkg_to_wheel, "-w", script.scratch_path)
+    result = script.pip(
+        "wheel", "--no-build-isolation", pkg_to_wheel, "-w", script.scratch_path
+    )
     assert "Installing build dependencies" not in result.stdout, result.stdout
 
     wheel_file_name = f"simplewheel-1.0-py{pyversion[0]}-none-any.whl"
diff --git a/tests/lib/__init__.py b/tests/lib/__init__.py
index 78fe3604480..1b9d1b96350 100644
--- a/tests/lib/__init__.py
+++ b/tests/lib/__init__.py
@@ -14,6 +14,7 @@
 from contextlib import contextmanager
 from hashlib import sha256
 from io import BytesIO, StringIO
+from pathlib import Path
 from textwrap import dedent
 from typing import Any, AnyStr, Callable, Literal, Protocol, Union, cast
 from urllib.request import pathname2url
@@ -28,11 +29,11 @@
 from pip._internal.index.collector import LinkCollector
 from pip._internal.index.package_finder import PackageFinder
 from pip._internal.locations import get_major_minor_version
+from pip._internal.models.direct_url import DIRECT_URL_METADATA_NAME, DirectUrl
 from pip._internal.models.search_scope import SearchScope
 from pip._internal.models.selection_prefs import SelectionPreferences
 from pip._internal.models.target_python import TargetPython
 from pip._internal.network.session import PipSession
-from pip._internal.utils.egg_link import _egg_link_names
 
 from tests.lib.venv import VirtualEnvironment
 from tests.lib.wheel import make_wheel
@@ -50,10 +51,6 @@
 _FilesState = dict[str, Union[FoundDir, FoundFile]]
 
 
-def assert_paths_equal(actual: str, expected: str) -> None:
-    assert os.path.normpath(actual) == os.path.normpath(expected)
-
-
 def create_file(path: str, contents: str | None = None) -> None:
     """Create a file on the path, with the given contents"""
     from pip._internal.utils.misc import ensure_dir
@@ -292,90 +289,71 @@ def files_updated(self) -> FoundFiles:
     def files_deleted(self) -> FoundFiles:
         return FoundFiles(self._impl.files_deleted)
 
-    def _get_egg_link_path_created(self, egg_link_paths: list[str]) -> str | None:
-        for egg_link_path in egg_link_paths:
-            if egg_link_path in self.files_created:
-                return egg_link_path
+    def get_created_direct_url_path(self, pkg: str) -> Path | None:
+        dist_info_prefix = canonicalize_name(pkg).replace("-", "_") + "-"
+        for filename in self.files_created:
+            if (
+                filename.name == DIRECT_URL_METADATA_NAME
+                and filename.parent.name.endswith(".dist-info")
+                and filename.parent.name.startswith(dist_info_prefix)
+            ):
+                return self.test_env.base_path / filename
+        return None
+
+    def get_created_direct_url(self, pkg: str) -> DirectUrl | None:
+        direct_url_path = self.get_created_direct_url_path(pkg)
+        if direct_url_path:
+            with open(direct_url_path) as f:
+                return DirectUrl.from_json(f.read())
         return None
 
     def assert_installed(
         self,
         pkg_name: str,
+        *,
+        dist_name: str | None = None,
         editable: bool = True,
+        editable_vcs: bool = True,
         with_files: list[str] | None = None,
         without_files: list[str] | None = None,
-        without_egg_link: bool = False,
-        use_user_site: bool = False,
         sub_dir: str | None = None,
     ) -> None:
+        if dist_name is None:
+            dist_name = pkg_name
         with_files = with_files or []
         without_files = without_files or []
         e = self.test_env
 
-        if editable:
-            pkg_dir = e.venv / "src" / canonicalize_name(pkg_name)
+        if editable and editable_vcs:
+            pkg_dir = e.venv / "src" / canonicalize_name(dist_name)
             # If package was installed in a sub directory
             if sub_dir:
                 pkg_dir = pkg_dir / sub_dir
+        elif editable and not editable_vcs:
+            pkg_dir = None
+            assert not with_files
+            assert not without_files
         else:
-            without_egg_link = True
             pkg_dir = e.site_packages / pkg_name
 
-        if use_user_site:
-            egg_link_paths = [
-                e.user_site / egg_link_name
-                for egg_link_name in _egg_link_names(pkg_name)
-            ]
-        else:
-            egg_link_paths = [
-                e.site_packages / egg_link_name
-                for egg_link_name in _egg_link_names(pkg_name)
-            ]
-
-        egg_link_path_created = self._get_egg_link_path_created(egg_link_paths)
-        if without_egg_link:
-            if egg_link_path_created:
+        direct_url = self.get_created_direct_url(dist_name)
+        if not editable:
+            if direct_url and direct_url.is_local_editable():
                 raise TestFailure(
-                    f"unexpected egg link file created: {egg_link_path_created!r}\n"
+                    "unexpected editable direct_url.json created: "
+                    f"{self.get_created_direct_url_path(dist_name)!r}\n"
                     f"{self}"
                 )
         else:
-            if not egg_link_path_created:
+            if not direct_url or not direct_url.is_local_editable():
                 raise TestFailure(
-                    f"expected egg link file missing: {egg_link_paths!r}\n{self}"
-                )
-
-            egg_link_file = self.files_created[egg_link_path_created]
-            egg_link_contents = egg_link_file.bytes.replace(os.linesep, "\n")
-
-            # FIXME: I don't understand why there's a trailing . here
-            if not (
-                egg_link_contents.endswith("\n.")
-                and egg_link_contents[:-2].endswith(os.fspath(pkg_dir))
-            ):
-                expected_ending = f"{pkg_dir}\n."
-                raise TestFailure(
-                    textwrap.dedent(
-                        f"""
-                        Incorrect egg_link file {egg_link_file!r}
-                        Expected ending: {expected_ending!r}
-                        ------- Actual contents -------
-                        {egg_link_contents!r}
-                        -------------------------------
-                        """
-                    ).strip()
+                    f"{dist_name!r} not installed as editable: direct_url.json "
+                    "not found or not editable\n"
+                    f"{self.get_created_direct_url_path(dist_name)!r}\n"
+                    f"{self}"
                 )
 
-        if use_user_site:
-            pth_file = e.user_site / "easy-install.pth"
-        else:
-            pth_file = e.site_packages / "easy-install.pth"
-
-        if (pth_file in self.files_updated) == without_egg_link:
-            maybe = "" if without_egg_link else "not "
-            raise TestFailure(f"{pth_file} unexpectedly {maybe}updated by install")
-
-        if (pkg_dir in self.files_created) == (os.curdir in without_files):
+        if pkg_dir and (pkg_dir in self.files_created) == (os.curdir in without_files):
             maybe = "not " if os.curdir in without_files else ""
             files = sorted(p.as_posix() for p in self.files_created)
             raise TestFailure(
@@ -728,6 +706,7 @@ def pip_install_local(
     ) -> TestPipResult:
         return self.pip(
             "install",
+            "--no-build-isolation",
             "--no-index",
             "--find-links",
             pathlib.Path(DATA_DIR, "packages").as_uri(),
@@ -756,6 +735,17 @@ def assert_not_installed(self, *args: str) -> None:
         expected = {canonicalize_name(k) for k in args}
         assert not (expected & installed), f"{expected!r} contained in {installed!r}"
 
+    def assert_installed_editable(self, dist_name: str) -> None:
+        dist_name = canonicalize_name(dist_name)
+        ret = self.pip("list", "--format=json")
+        installed = json.loads(ret.stdout)
+        assert any(
+            x
+            for x in installed
+            if canonicalize_name(x["name"]) == dist_name
+            and x.get("editable_project_location")
+        )
+
 
 # FIXME ScriptTest does something similar, but only within a single
 # ProcResult; this generalizes it so states can be compared across
@@ -1224,8 +1214,7 @@ def create_basic_sdist_for_package(
     version: str,
     extra_files: dict[str, str] | None = None,
     *,
-    fails_egg_info: bool = False,
-    fails_bdist_wheel: bool = False,
+    fails_build: bool = False,
     depends: list[str] | None = None,
     setup_py_prelude: str = "",
 ) -> pathlib.Path:
@@ -1237,14 +1226,10 @@ def create_basic_sdist_for_package(
 
             {setup_py_prelude}
 
-            fails_bdist_wheel = {fails_bdist_wheel!r}
-            fails_egg_info = {fails_egg_info!r}
-
-            if fails_egg_info and "egg_info" in sys.argv:
-                raise Exception("Simulated failure for generating metadata.")
+            fails_build = {fails_build!r}
 
-            if fails_bdist_wheel and "bdist_wheel" in sys.argv:
-                raise Exception("Simulated failure for building a wheel.")
+            if fails_build:
+                raise Exception("Simulated build failure.")
 
             setup(name={name!r}, version={version!r},
                 install_requires={depends!r})
@@ -1254,8 +1239,7 @@ def create_basic_sdist_for_package(
             version=version,
             depends=depends or [],
             setup_py_prelude=setup_py_prelude,
-            fails_bdist_wheel=fails_bdist_wheel,
-            fails_egg_info=fails_egg_info,
+            fails_build=fails_build,
         ),
     }
 
diff --git a/tests/lib/direct_url.py b/tests/lib/direct_url.py
deleted file mode 100644
index 3049da9c1d2..00000000000
--- a/tests/lib/direct_url.py
+++ /dev/null
@@ -1,27 +0,0 @@
-from __future__ import annotations
-
-import os
-import re
-from pathlib import Path
-
-from pip._internal.models.direct_url import DIRECT_URL_METADATA_NAME, DirectUrl
-
-from tests.lib import TestPipResult
-
-
-def get_created_direct_url_path(result: TestPipResult, pkg: str) -> Path | None:
-    direct_url_metadata_re = re.compile(
-        pkg + r"-[\d\.]+\.dist-info." + DIRECT_URL_METADATA_NAME + r"$"
-    )
-    for filename in result.files_created:
-        if direct_url_metadata_re.search(os.fspath(filename)):
-            return result.test_env.base_path / filename
-    return None
-
-
-def get_created_direct_url(result: TestPipResult, pkg: str) -> DirectUrl | None:
-    direct_url_path = get_created_direct_url_path(result, pkg)
-    if direct_url_path:
-        with open(direct_url_path) as f:
-            return DirectUrl.from_json(f.read())
-    return None
diff --git a/tests/unit/resolution_resolvelib/conftest.py b/tests/unit/resolution_resolvelib/conftest.py
index ee2633afac9..436abddbd4d 100644
--- a/tests/unit/resolution_resolvelib/conftest.py
+++ b/tests/unit/resolution_resolvelib/conftest.py
@@ -35,7 +35,7 @@ def finder(data: TestData) -> PackageFinder:
 def preparer(finder: PackageFinder) -> Iterator[RequirementPreparer]:
     session = PipSession()
     rc = InstallCommand("x", "y")
-    o = rc.parse_args([])
+    o = rc.parse_args(["--no-build-isolation"])
 
     with global_tempdir_manager():
         with TempDirectory() as tmp:
diff --git a/tests/unit/test_options.py b/tests/unit/test_options.py
index c996bee8eca..1052558ab2f 100644
--- a/tests/unit/test_options.py
+++ b/tests/unit/test_options.py
@@ -198,91 +198,6 @@ def test_cache_dir__PIP_NO_CACHE_DIR_invalid__with_no_cache_dir(
             main(["--no-cache-dir", "fake"])
 
 
-class TestUsePEP517Options:
-    """
-    Test options related to using --use-pep517.
-    """
-
-    def parse_args(self, args: list[str]) -> Values:
-        # We use DownloadCommand since that is one of the few Command
-        # classes with the use_pep517 options.
-        command = create_command("download")
-        options, args = command.parse_args(args)
-
-        return options
-
-    def test_no_option(self) -> None:
-        """
-        Test passing no option.
-        """
-        options = self.parse_args([])
-        assert options.use_pep517 is None
-
-    def test_use_pep517(self) -> None:
-        """
-        Test passing --use-pep517.
-        """
-        options = self.parse_args(["--use-pep517"])
-        assert options.use_pep517 is True
-
-    def test_no_use_pep517(self) -> None:
-        """
-        Test passing --no-use-pep517.
-        """
-        options = self.parse_args(["--no-use-pep517"])
-        assert options.use_pep517 is False
-
-    def test_PIP_USE_PEP517_true(self, monkeypatch: pytest.MonkeyPatch) -> None:
-        """
-        Test setting PIP_USE_PEP517 to "true".
-        """
-        monkeypatch.setenv("PIP_USE_PEP517", "true")
-        options = self.parse_args([])
-        # This is an int rather than a boolean because strtobool() in pip's
-        # configuration code returns an int.
-        assert options.use_pep517 == 1
-
-    def test_PIP_USE_PEP517_false(self, monkeypatch: pytest.MonkeyPatch) -> None:
-        """
-        Test setting PIP_USE_PEP517 to "false".
-        """
-        monkeypatch.setenv("PIP_USE_PEP517", "false")
-        options = self.parse_args([])
-        # This is an int rather than a boolean because strtobool() in pip's
-        # configuration code returns an int.
-        assert options.use_pep517 == 0
-
-    def test_use_pep517_and_PIP_USE_PEP517_false(
-        self, monkeypatch: pytest.MonkeyPatch
-    ) -> None:
-        """
-        Test passing --use-pep517 and setting PIP_USE_PEP517 to "false".
-        """
-        monkeypatch.setenv("PIP_USE_PEP517", "false")
-        options = self.parse_args(["--use-pep517"])
-        assert options.use_pep517 is True
-
-    def test_no_use_pep517_and_PIP_USE_PEP517_true(
-        self, monkeypatch: pytest.MonkeyPatch
-    ) -> None:
-        """
-        Test passing --no-use-pep517 and setting PIP_USE_PEP517 to "true".
-        """
-        monkeypatch.setenv("PIP_USE_PEP517", "true")
-        options = self.parse_args(["--no-use-pep517"])
-        assert options.use_pep517 is False
-
-    def test_PIP_NO_USE_PEP517(
-        self, monkeypatch: pytest.MonkeyPatch, capsys: pytest.CaptureFixture[str]
-    ) -> None:
-        """
-        Test setting PIP_NO_USE_PEP517, which isn't allowed.
-        """
-        monkeypatch.setenv("PIP_NO_USE_PEP517", "true")
-        with assert_option_error(capsys, expected="--no-use-pep517 error"):
-            self.parse_args([])
-
-
 class TestOptionsInterspersed(AddFakeCommandMixin):
     def test_general_option_after_subcommand(self) -> None:
         # FakeCommand intentionally returns the wrong type.
diff --git a/tests/unit/test_pep517.py b/tests/unit/test_pep517.py
index 27008de79c2..86e6ca70e34 100644
--- a/tests/unit/test_pep517.py
+++ b/tests/unit/test_pep517.py
@@ -4,72 +4,9 @@
 
 import pytest
 
-from pip._internal.exceptions import InstallationError, InvalidPyProjectBuildRequires
+from pip._internal.exceptions import InvalidPyProjectBuildRequires
 from pip._internal.req import InstallRequirement
 
-from tests.lib import TestData
-
-
-@pytest.mark.parametrize(
-    "source, expected",
-    [
-        ("pep517_setup_and_pyproject", True),
-        ("pep517_setup_only", False),
-        ("pep517_pyproject_only", True),
-    ],
-)
-def test_use_pep517(shared_data: TestData, source: str, expected: bool) -> None:
-    """
-    Test that we choose correctly between PEP 517 and legacy code paths
-    """
-    src = shared_data.src.joinpath(source)
-    req = InstallRequirement(None, None)
-    req.source_dir = os.fspath(src)  # make req believe it has been unpacked
-    req.load_pyproject_toml()
-    assert req.use_pep517 is expected
-
-
-def test_use_pep517_rejects_setup_cfg_only(shared_data: TestData) -> None:
-    """
-    Test that projects with setup.cfg but no pyproject.toml are rejected.
-    """
-    src = shared_data.src.joinpath("pep517_setup_cfg_only")
-    req = InstallRequirement(None, None)
-    req.source_dir = os.fspath(src)  # make req believe it has been unpacked
-    with pytest.raises(InstallationError) as e:
-        req.load_pyproject_toml()
-    err_msg = e.value.args[0]
-    assert (
-        "does not appear to be a Python project: "
-        "neither 'setup.py' nor 'pyproject.toml' found" in err_msg
-    )
-
-
-@pytest.mark.parametrize(
-    "source, msg",
-    [
-        ("pep517_setup_and_pyproject", "specifies a build backend"),
-        ("pep517_pyproject_only", "does not have a setup.py"),
-    ],
-)
-def test_disabling_pep517_invalid(shared_data: TestData, source: str, msg: str) -> None:
-    """
-    Test that we fail if we try to disable PEP 517 when it's not acceptable
-    """
-    src = shared_data.src.joinpath(source)
-    req = InstallRequirement(None, None)
-    req.source_dir = os.fspath(src)  # make req believe it has been unpacked
-
-    # Simulate --no-use-pep517
-    req.use_pep517 = False
-
-    with pytest.raises(InstallationError) as e:
-        req.load_pyproject_toml()
-
-    err_msg = e.value.args[0]
-    assert "Disabling PEP 517 processing is invalid" in err_msg
-    assert msg in err_msg
-
 
 @pytest.mark.parametrize(
     "spec", [("./foo",), ("git+https://example.com/pkg@dev#egg=myproj",)]
diff --git a/tests/unit/test_req.py b/tests/unit/test_req.py
index 0a245fab6a3..38f9207de82 100644
--- a/tests/unit/test_req.py
+++ b/tests/unit/test_req.py
@@ -90,11 +90,11 @@ def _basic_resolver(
         finder: PackageFinder,
         require_hashes: bool = False,
         wheel_cache: WheelCache | None = None,
+        build_isolation: bool = True,
     ) -> Iterator[Resolver]:
         make_install_req = partial(
             install_req_from_req_string,
             isolated=False,
-            use_pep517=None,
         )
         session = PipSession()
 
@@ -104,7 +104,7 @@ def _basic_resolver(
                 build_dir=os.path.join(self.tempdir, "build"),
                 src_dir=os.path.join(self.tempdir, "src"),
                 download_dir=None,
-                build_isolation=True,
+                build_isolation=build_isolation,
                 build_isolation_installer=installer,
                 check_build_deps=False,
                 build_tracker=tracker,
@@ -166,7 +166,7 @@ def test_environment_marker_extras(self, data: TestData) -> None:
         req.user_supplied = True
         reqset.add_unnamed_requirement(req)
         finder = make_test_finder(find_links=[data.find_links])
-        with self._basic_resolver(finder) as resolver:
+        with self._basic_resolver(finder, build_isolation=False) as resolver:
             reqset = resolver.resolve(reqset.all_requirements, True)
         assert not reqset.has_requirement("simple")
 
@@ -319,7 +319,9 @@ def test_unhashed_deps_on_require_hashes(self, data: TestData) -> None:
             )
         )
 
-        with self._basic_resolver(finder, require_hashes=True) as resolver:
+        with self._basic_resolver(
+            finder, require_hashes=True, build_isolation=False
+        ) as resolver:
             with pytest.raises(
                 HashErrors,
                 match=(
@@ -360,7 +362,7 @@ def test_hashed_deps_on_require_hashes(self) -> None:
     def test_download_info_find_links(self, data: TestData) -> None:
         """Test that download_info is set for requirements via find_links."""
         finder = make_test_finder(find_links=[data.find_links])
-        with self._basic_resolver(finder) as resolver:
+        with self._basic_resolver(finder, build_isolation=False) as resolver:
             ireq = get_processed_req_from_line("simple")
             reqset = resolver.resolve([ireq], True)
             assert len(reqset.all_requirements) == 1
@@ -385,7 +387,7 @@ def test_download_info_index_url(self) -> None:
     def test_download_info_web_archive(self) -> None:
         """Test that download_info is set for requirements from a web archive."""
         finder = make_test_finder()
-        with self._basic_resolver(finder) as resolver:
+        with self._basic_resolver(finder, build_isolation=False) as resolver:
             ireq = get_processed_req_from_line(
                 "pip-test-package @ "
                 "https://github.com/pypa/pip-test-package/tarball/0.1.1"
@@ -495,7 +497,7 @@ def test_download_info_local_wheel(self, data: TestData) -> None:
     def test_download_info_local_dir(self, data: TestData) -> None:
         """Test that download_info is set for requirements from a local dir."""
         finder = make_test_finder()
-        with self._basic_resolver(finder) as resolver:
+        with self._basic_resolver(finder, build_isolation=False) as resolver:
             ireq_url = data.packages.joinpath("FSPkg").as_uri()
             ireq = get_processed_req_from_line(f"FSPkg @ {ireq_url}")
             reqset = resolver.resolve([ireq], True)
@@ -508,7 +510,7 @@ def test_download_info_local_dir(self, data: TestData) -> None:
     def test_download_info_local_editable_dir(self, data: TestData) -> None:
         """Test that download_info is set for requirements from a local editable dir."""
         finder = make_test_finder()
-        with self._basic_resolver(finder) as resolver:
+        with self._basic_resolver(finder, build_isolation=False) as resolver:
             ireq_url = data.packages.joinpath("FSPkg").as_uri()
             ireq = get_processed_req_from_line(f"-e {ireq_url}#egg=FSPkg")
             reqset = resolver.resolve([ireq], True)
@@ -523,7 +525,7 @@ def test_download_info_local_editable_dir(self, data: TestData) -> None:
     def test_download_info_vcs(self) -> None:
         """Test that download_info is set for requirements from git."""
         finder = make_test_finder()
-        with self._basic_resolver(finder) as resolver:
+        with self._basic_resolver(finder, build_isolation=False) as resolver:
             ireq = get_processed_req_from_line(
                 "pip-test-package @ git+https://github.com/pypa/pip-test-package"
             )
@@ -792,9 +794,7 @@ def test_install_req_drop_extras(self, inp: str, out: str) -> None:
         # all else should be the same
         assert without_extras.link == req.link
         assert without_extras.markers == req.markers
-        assert without_extras.use_pep517 == req.use_pep517
         assert without_extras.isolated == req.isolated
-        assert without_extras.global_options == req.global_options
         assert without_extras.hash_options == req.hash_options
         assert without_extras.constraint == req.constraint
         assert without_extras.config_settings == req.config_settings
@@ -841,9 +841,7 @@ def test_install_req_extend_extras(
         # all else should be the same
         assert extended.link == req.link
         assert extended.markers == req.markers
-        assert extended.use_pep517 == req.use_pep517
         assert extended.isolated == req.isolated
-        assert extended.global_options == req.global_options
         assert extended.hash_options == req.hash_options
         assert extended.constraint == req.constraint
         assert extended.config_settings == req.config_settings
diff --git a/tests/unit/test_req_file.py b/tests/unit/test_req_file.py
index 248171c7b5c..88fc4c58bb9 100644
--- a/tests/unit/test_req_file.py
+++ b/tests/unit/test_req_file.py
@@ -33,7 +33,7 @@
 )
 from pip._internal.req.req_install import InstallRequirement
 
-from tests.lib import TestData, make_test_finder, requirements_file
+from tests.lib import TestData, make_test_finder
 
 
 @pytest.fixture
@@ -422,13 +422,9 @@ def test_recursive_relative_requirements_file(
             list(parse_requirements(filename=str(root_req_file), session=session))
 
     def test_options_on_a_requirement_line(self, line_processor: LineProcessor) -> None:
-        line = (
-            'SomeProject --global-option="yo3" --global-option "yo4" '
-            '--config-settings="yo3=yo4" --config-settings "yo1=yo2"'
-        )
+        line = 'SomeProject --config-settings="yo3=yo4" --config-settings "yo1=yo2"'
         filename = "filename"
         req = line_processor(line, filename, 1)[0]
-        assert req.global_options == ["yo3", "yo4"]
         assert req.config_settings == {"yo3": "yo4", "yo1": "yo2"}
 
     def test_hash_options(self, line_processor: LineProcessor) -> None:
@@ -937,29 +933,6 @@ def test_req_file_no_finder(self, tmpdir: Path) -> None:
 
         parse_reqfile(tmpdir.joinpath("req.txt"), session=PipSession())
 
-    def test_install_requirements_with_options(
-        self,
-        tmpdir: Path,
-        finder: PackageFinder,
-        session: PipSession,
-        options: mock.Mock,
-    ) -> None:
-        global_option = "--dry-run"
-
-        content = f"""
-        --only-binary :all:
-        INITools==2.0 --global-option="{global_option}"
-        """
-
-        with requirements_file(content, tmpdir) as reqs_file:
-            req = next(
-                parse_reqfile(
-                    reqs_file.resolve(), finder=finder, options=options, session=session
-                )
-            )
-
-        assert req.global_options == [global_option]
-
     @pytest.mark.parametrize(
         "raw_req_file,expected_name,expected_spec",
         [
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 147728b4e97..a9f7beea296 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -51,7 +51,6 @@
     split_auth_netloc_from_url,
     tabulate,
 )
-from pip._internal.utils.setuptools_build import make_setuptools_shim_args
 
 
 class Tests_EgglinkPath:
@@ -932,59 +931,6 @@ def test_deprecated_message_reads_well_future() -> None:
     )
 
 
-def test_make_setuptools_shim_args() -> None:
-    # Test all arguments at once, including the overall ordering.
-    args = make_setuptools_shim_args(
-        "/dir/path/setup.py",
-        global_options=["--some", "--option"],
-        no_user_config=True,
-        unbuffered_output=True,
-    )
-
-    assert args[1:3] == ["-u", "-c"]
-    assert args[4:] == ["--some", "--option", "--no-user-cfg"]
-
-    shim = args[3]
-    # Spot-check key aspects of the command string.
-    assert "import setuptools" in shim
-    assert "'/dir/path/setup.py'" in args[3]
-    assert "sys.argv[0] = __file__" in args[3]
-
-
-@pytest.mark.parametrize("global_options", [None, [], ["--some", "--option"]])
-def test_make_setuptools_shim_args__global_options(
-    global_options: list[str] | None,
-) -> None:
-    args = make_setuptools_shim_args(
-        "/dir/path/setup.py",
-        global_options=global_options,
-    )
-
-    if global_options:
-        assert len(args) == 5
-        for option in global_options:
-            assert option in args
-    else:
-        assert len(args) == 3
-
-
-@pytest.mark.parametrize("no_user_config", [False, True])
-def test_make_setuptools_shim_args__no_user_config(no_user_config: bool) -> None:
-    args = make_setuptools_shim_args(
-        "/dir/path/setup.py",
-        no_user_config=no_user_config,
-    )
-    assert ("--no-user-cfg" in args) == no_user_config
-
-
-@pytest.mark.parametrize("unbuffered_output", [False, True])
-def test_make_setuptools_shim_args__unbuffered_output(unbuffered_output: bool) -> None:
-    args = make_setuptools_shim_args(
-        "/dir/path/setup.py", unbuffered_output=unbuffered_output
-    )
-    assert ("-u" in args) == unbuffered_output
-
-
 @pytest.mark.parametrize(
     "isatty,no_stdin,expected",
     [
diff --git a/tests/unit/test_wheel.py b/tests/unit/test_wheel.py
index 96dc424f1c4..e0ac6497b78 100644
--- a/tests/unit/test_wheel.py
+++ b/tests/unit/test_wheel.py
@@ -3,7 +3,6 @@
 from __future__ import annotations
 
 import csv
-import logging
 import os
 import pathlib
 import sys
@@ -26,7 +25,6 @@
     DirectUrl,
 )
 from pip._internal.models.scheme import Scheme
-from pip._internal.operations.build.wheel_legacy import get_legacy_build_wheel_path
 from pip._internal.operations.install import wheel
 from pip._internal.operations.install.wheel import (
     InstalledCSVRow,
@@ -37,68 +35,10 @@
 from pip._internal.utils.misc import hash_file
 from pip._internal.utils.unpacking import unpack_file
 
-from tests.lib import DATA_DIR, TestData, assert_paths_equal
+from tests.lib import DATA_DIR, TestData
 from tests.lib.wheel import make_wheel
 
 
-def call_get_legacy_build_wheel_path(
-    caplog: pytest.LogCaptureFixture, names: list[str]
-) -> str | None:
-    wheel_path = get_legacy_build_wheel_path(
-        names=names,
-        temp_dir="/tmp/abcd",
-        name="pendulum",
-        command_args=["arg1", "arg2"],
-        command_output="output line 1\noutput line 2\n",
-    )
-    return wheel_path
-
-
-def test_get_legacy_build_wheel_path(caplog: pytest.LogCaptureFixture) -> None:
-    actual = call_get_legacy_build_wheel_path(caplog, names=["name"])
-    assert actual is not None
-    assert_paths_equal(actual, "/tmp/abcd/name")
-    assert not caplog.records
-
-
-def test_get_legacy_build_wheel_path__no_names(
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    caplog.set_level(logging.INFO)
-    actual = call_get_legacy_build_wheel_path(caplog, names=[])
-    assert actual is None
-    assert len(caplog.records) == 1
-    record = caplog.records[0]
-    assert record.levelname == "WARNING"
-    assert record.message.splitlines() == [
-        "Legacy build of wheel for 'pendulum' created no files.",
-        "Command arguments: arg1 arg2",
-        "Command output: [use --verbose to show]",
-    ]
-
-
-def test_get_legacy_build_wheel_path__multiple_names(
-    caplog: pytest.LogCaptureFixture,
-) -> None:
-    caplog.set_level(logging.INFO)
-    # Deliberately pass the names in non-sorted order.
-    actual = call_get_legacy_build_wheel_path(
-        caplog,
-        names=["name2", "name1"],
-    )
-    assert actual is not None
-    assert_paths_equal(actual, "/tmp/abcd/name1")
-    assert len(caplog.records) == 1
-    record = caplog.records[0]
-    assert record.levelname == "WARNING"
-    assert record.message.splitlines() == [
-        "Legacy build of wheel for 'pendulum' created more than one file.",
-        "Filenames (choosing first): ['name1', 'name2']",
-        "Command arguments: arg1 arg2",
-        "Command output: [use --verbose to show]",
-    ]
-
-
 @pytest.mark.parametrize(
     "console_scripts",
     [
diff --git a/tests/unit/test_wheel_builder.py b/tests/unit/test_wheel_builder.py
index 0547ac818bc..1fc9e789256 100644
--- a/tests/unit/test_wheel_builder.py
+++ b/tests/unit/test_wheel_builder.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import logging
 import os
 from dataclasses import dataclass
 from pathlib import Path
@@ -10,7 +9,6 @@
 
 from pip._internal import wheel_builder
 from pip._internal.models.link import Link
-from pip._internal.operations.build.wheel_legacy import format_command_result
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.vcs.git import Git
 
@@ -43,52 +41,13 @@ class ReqMock:
     link: Link | None = None
     constraint: bool = False
     source_dir: str | None = "/tmp/pip-install-123/pendulum"
-    use_pep517: bool = True
     supports_pyproject_editable: bool = False
 
 
 @pytest.mark.parametrize(
     "req, expected",
     [
-        # We build, whether pep 517 is enabled or not.
-        (ReqMock(use_pep517=True), True),
-        (ReqMock(use_pep517=False), True),
-        # We don't build reqs that are already wheels.
-        (ReqMock(is_wheel=True), False),
-        # We build editables if the backend supports PEP 660.
-        (ReqMock(editable=True, use_pep517=False), False),
-        (
-            ReqMock(editable=True, use_pep517=True, supports_pyproject_editable=True),
-            True,
-        ),
-        (
-            ReqMock(editable=True, use_pep517=True, supports_pyproject_editable=False),
-            False,
-        ),
-        # By default (i.e. when binaries are allowed), VCS requirements
-        # should be built in install mode.
-        (
-            ReqMock(link=Link("git+https://g.c/org/repo"), use_pep517=True),
-            True,
-        ),
-        (
-            ReqMock(link=Link("git+https://g.c/org/repo"), use_pep517=False),
-            True,
-        ),
-    ],
-)
-def test_should_build_for_install_command(req: ReqMock, expected: bool) -> None:
-    should_build = wheel_builder.should_build_for_install_command(
-        cast(InstallRequirement, req),
-    )
-    assert should_build is expected
-
-
-@pytest.mark.parametrize(
-    "req, expected",
-    [
-        (ReqMock(editable=True, use_pep517=False), False),
-        (ReqMock(editable=True, use_pep517=True), False),
+        (ReqMock(editable=True), False),
         (ReqMock(source_dir=None), False),
         (ReqMock(link=Link("git+https://g.c/org/repo")), False),
         (ReqMock(link=Link("https://g.c/dist.tgz")), False),
@@ -112,56 +71,3 @@ def test_should_cache_git_sha(tmpdir: Path) -> None:
     url = "git+https://g.c/o/r@master#egg=mypkg"
     req = ReqMock(link=Link(url), source_dir=repo_path)
     assert not wheel_builder._should_cache(cast(InstallRequirement, req))
-
-
-def test_format_command_result__INFO(caplog: pytest.LogCaptureFixture) -> None:
-    caplog.set_level(logging.INFO)
-    actual = format_command_result(
-        # Include an argument with a space to test argument quoting.
-        command_args=["arg1", "second arg"],
-        command_output="output line 1\noutput line 2\n",
-    )
-    assert actual.splitlines() == [
-        "Command arguments: arg1 'second arg'",
-        "Command output: [use --verbose to show]",
-    ]
-
-
-@pytest.mark.parametrize(
-    "command_output",
-    [
-        # Test trailing newline.
-        "output line 1\noutput line 2\n",
-        # Test no trailing newline.
-        "output line 1\noutput line 2",
-    ],
-)
-def test_format_command_result__DEBUG(
-    caplog: pytest.LogCaptureFixture, command_output: str
-) -> None:
-    caplog.set_level(logging.DEBUG)
-    actual = format_command_result(
-        command_args=["arg1", "arg2"],
-        command_output=command_output,
-    )
-    assert actual.splitlines() == [
-        "Command arguments: arg1 arg2",
-        "Command output:",
-        "output line 1",
-        "output line 2",
-    ]
-
-
-@pytest.mark.parametrize("log_level", ["DEBUG", "INFO"])
-def test_format_command_result__empty_output(
-    caplog: pytest.LogCaptureFixture, log_level: str
-) -> None:
-    caplog.set_level(log_level)
-    actual = format_command_result(
-        command_args=["arg1", "arg2"],
-        command_output="",
-    )
-    assert actual.splitlines() == [
-        "Command arguments: arg1 arg2",
-        "Command output: None",
-    ]