diff --git a/tools/ports/__init__.py b/tools/ports/__init__.py
index 56ab677311ba5..e07442989e1b6 100644
--- a/tools/ports/__init__.py
+++ b/tools/ports/__init__.py
@@ -248,7 +248,7 @@ def build_port(src_dir, output_path, port_name, includes=[], flags=[], cxxflags=
       os.makedirs(build_dir, exist_ok=True)
       ninja_file = os.path.join(build_dir, 'build.ninja')
       system_libs.ensure_sysroot()
-      system_libs.create_ninja_file(srcs, ninja_file, output_path, cflags=cflags)
+      system_libs.create_ninja_file(srcs, ninja_file, output_path, cflags=cflags, cxxflags=cflags + cxxflags)
       if not os.getenv('EMBUILDER_PORT_BUILD_DEFERRED'):
         system_libs.run_ninja(build_dir)
     else:
diff --git a/tools/system_libs.py b/tools/system_libs.py
index 063f82abb4c40..9e3453ac9501c 100644
--- a/tools/system_libs.py
+++ b/tools/system_libs.py
@@ -180,7 +180,7 @@ def escape_ninja_path(path):
   return re.sub(r'([ :$])', r'$\1', path)
 
 
-def create_ninja_file(input_files, filename, libname, cflags, asflags=None, customize_build_flags=None):
+def create_ninja_file(input_files, filename, libname, cflags, cxxflags, asflags=None, customize_build_flags=None):
   if asflags is None:
     asflags = []
 
@@ -193,6 +193,7 @@ def create_ninja_file(input_files, filename, libname, cflags, asflags=None, cust
 
 ASFLAGS = {join_cmd(asflags)}
 CFLAGS = {join_cmd(cflags)}
+CXXFLAGS = {join_cmd(cxxflags)}
 EMCC = {shared.EMCC}
 EMXX = {shared.EMXX}
 EMAR = {shared.EMAR}
@@ -204,7 +205,7 @@ def create_ninja_file(input_files, filename, libname, cflags, asflags=None, cust
 
 rule cxx
   depfile = $out.d
-  command = $EMXX -MD -MF $out.d $CFLAGS -c $in -o $out
+  command = $EMXX -MD -MF $out.d $CXXFLAGS -c $in -o $out
   description = CXX $out
 
 rule asm
@@ -266,12 +267,15 @@ def create_ninja_file(input_files, filename, libname, cflags, asflags=None, cust
           flags = cflags
         case _:
           cmd = 'cxx'
-          flags = cflags
+          flags = cxxflags
       out += f'build {escape_ninja_path(o)}: {cmd} {escape_ninja_path(src)}\n'
       if customize_build_flags:
         custom_flags = customize_build_flags(flags, src)
         if custom_flags != flags:
-          out += f'  CFLAGS = {join_cmd(custom_flags)}'
+          if flags == cflags:
+            out += f'  CFLAGS = {join_cmd(custom_flags)}'
+          else:
+            out += f'  CXXFLAGS = {join_cmd(custom_flags)}'
       out += '\n'
 
     objects = sorted(objects, key=objectfile_sort_key)
@@ -475,10 +479,12 @@ def generate_ninja(self, build_dir, libname):
     self.build_dir = build_dir
 
     cflags = self.get_cflags()
+    cxxflags = self.get_cxxflags()
+
     asflags = get_base_cflags(self.build_dir, preprocess=False)
     input_files = self.get_files()
     ninja_file = os.path.join(build_dir, 'build.ninja')
-    create_ninja_file(input_files, ninja_file, libname, cflags, asflags=asflags, customize_build_flags=self.customize_build_cmd)
+    create_ninja_file(input_files, ninja_file, libname, cflags, cxxflags, asflags=asflags, customize_build_flags=self.customize_build_cmd)
 
   def build_objects(self, build_dir):
     """
@@ -493,7 +499,6 @@ def build_objects(self, build_dir):
     commands = []
     objects = set()
     objects_lowercase = set()
-    cflags = self.get_cflags()
     for src in self.get_files():
       ext = utils.suffix(src)
       if ext in {'.s', '.S', '.c'}:
@@ -506,8 +511,10 @@ def build_objects(self, build_dir):
         # pre-processor flags such as `-I` and `-D` but we still want core flags such as
         # `-sMEMORY64`.
         cmd += get_base_cflags(self.build_dir, preprocess=False)
+      elif ext in {'.c', '.S'}:
+        cmd += self.get_cflags()
       else:
-        cmd += cflags
+        cmd += self.get_cxxflags()
       cmd = self.customize_build_cmd(cmd, src)
 
       object_basename = utils.unsuffixed_basename(src)
@@ -600,6 +607,13 @@ def get_cflags(self):
       cflags += ['-I' + utils.path_from_root(i) for i in self._inherit_list('includes')]
     return cflags
 
+  def get_cxxflags(self):
+    """
+    Returns the list of flags to pass to em++ when building this variation
+    of the library.
+    """
+    return self.get_cflags()
+
   def get_base_name_prefix(self):
     """
     Returns the base name of the library without any suffixes.
@@ -1744,7 +1758,7 @@ def __init__(self, **kwargs):
   def can_use(self):
     return super().can_use() and self.eh_mode in (Exceptions.WASM_LEGACY, Exceptions.WASM)
 
-  def get_cflags(self):
+  def _get_common_flags(self):
     cflags = super().get_cflags()
     cflags.append('-DNDEBUG')
     if not self.is_mt and not self.is_ww:
@@ -1754,8 +1768,15 @@ def get_cflags(self):
         cflags.append('-D_LIBUNWIND_HAS_NO_EXCEPTIONS')
       case Exceptions.EMSCRIPTEN:
         cflags.append('-D__EMSCRIPTEN_EXCEPTIONS__')
+
     return cflags
 
+  def get_cflags(self):
+    return self._get_common_flags() + ['-std=c23']
+
+  def get_cxxflags(self):
+    return self._get_common_flags() + ['-std=c++23']
+
 
 class libmalloc(MTLibrary):
   name = 'libmalloc'