diff --git a/libcxx/include/__config b/libcxx/include/__config
index b4c081dcdff1b..dfc101954bddb 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -721,6 +721,12 @@ typedef __char32_t char32_t;
 #    define _LIBCPP_DEPRECATED_(m)
 #  endif
 
+#  if defined(__DEPRECATED) && __DEPRECATED && !defined(_LIBCPP_DISABLE_DEPRECATION_WARNINGS) && !__building_module(std)
+#    define _LIBCPP_DIAGNOSE_DEPRECATED_HEADERS 1
+#  else
+#    define _LIBCPP_DIAGNOSE_DEPRECATED_HEADERS 0
+#  endif
+
 #  if !defined(_LIBCPP_CXX03_LANG)
 #    define _LIBCPP_DEPRECATED_IN_CXX11 _LIBCPP_DEPRECATED
 #  else
diff --git a/libcxx/include/ccomplex b/libcxx/include/ccomplex
index ee7e088aac54d..bade696b95c70 100644
--- a/libcxx/include/ccomplex
+++ b/libcxx/include/ccomplex
@@ -26,18 +26,10 @@
 #    pragma GCC system_header
 #  endif
 
-#  if _LIBCPP_STD_VER >= 20
-
-using __standard_header_ccomplex
-    _LIBCPP_DEPRECATED_("removed in C++20. Include <complex> instead.") _LIBCPP_NODEBUG = void;
-using __use_standard_header_ccomplex _LIBCPP_NODEBUG                                    = __standard_header_ccomplex;
-
-#  elif _LIBCPP_STD_VER >= 17
-
-using __standard_header_ccomplex _LIBCPP_DEPRECATED_("Include <complex> instead.") _LIBCPP_NODEBUG = void;
-using __use_standard_header_ccomplex _LIBCPP_NODEBUG = __standard_header_ccomplex;
-
+#  if _LIBCPP_STD_VER >= 17 && _LIBCPP_DIAGNOSE_DEPRECATED_HEADERS
+#    warning <ccomplex> is removed in C++20. Include <complex> instead.
 #  endif
+
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_CCOMPLEX
diff --git a/libcxx/include/ciso646 b/libcxx/include/ciso646
index 34164362dc10d..f4b1d6fa78ce7 100644
--- a/libcxx/include/ciso646
+++ b/libcxx/include/ciso646
@@ -24,13 +24,10 @@
 #    pragma GCC system_header
 #  endif
 
-#  if _LIBCPP_STD_VER >= 20
-
-using __standard_header_ciso646
-    _LIBCPP_DEPRECATED_("removed in C++20. Include <version> instead.") _LIBCPP_NODEBUG = void;
-using __use_standard_header_ciso646 _LIBCPP_NODEBUG                                     = __standard_header_ciso646;
-
+#  if _LIBCPP_STD_VER >= 20 && _LIBCPP_DIAGNOSE_DEPRECATED_HEADERS
+#    warning <ciso646> is removed in C++20. Include <version> instead.
 #  endif
+
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_CISO646
diff --git a/libcxx/include/cstdalign b/libcxx/include/cstdalign
index 7f8dd1e1fbaf8..60b2963c10fb4 100644
--- a/libcxx/include/cstdalign
+++ b/libcxx/include/cstdalign
@@ -43,17 +43,10 @@ Macros:
 #  undef __alignof_is_defined
 #  define __alignof_is_defined 1
 
-#  if _LIBCPP_STD_VER >= 20
-
-using __standard_header_cstdalign _LIBCPP_DEPRECATED_("removed in C++20.") _LIBCPP_NODEBUG = void;
-using __use_standard_header_cstdalign _LIBCPP_NODEBUG = __standard_header_cstdalign;
-
-#  elif _LIBCPP_STD_VER >= 17
-
-using __standard_header_cstdalign _LIBCPP_DEPRECATED _LIBCPP_NODEBUG = void;
-using __use_standard_header_cstdalign _LIBCPP_NODEBUG                = __standard_header_cstdalign;
-
+#  if _LIBCPP_STD_VER >= 17 && _LIBCPP_DIAGNOSE_DEPRECATED_HEADERS
+#    warning <cstdalign> is removed in C++20.
 #  endif
+
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_CSTDALIGN
diff --git a/libcxx/include/cstdbool b/libcxx/include/cstdbool
index a432d5f08b9ae..78b98699460dc 100644
--- a/libcxx/include/cstdbool
+++ b/libcxx/include/cstdbool
@@ -31,17 +31,10 @@ Macros:
 #  undef __bool_true_false_are_defined
 #  define __bool_true_false_are_defined 1
 
-#  if _LIBCPP_STD_VER >= 20
-
-using __standard_header_cstdbool _LIBCPP_DEPRECATED_("removed in C++20.") _LIBCPP_NODEBUG = void;
-using __use_standard_header_cstdbool _LIBCPP_NODEBUG                                      = __standard_header_cstdbool;
-
-#  elif _LIBCPP_STD_VER >= 17
-
-using __standard_header_cstdbool _LIBCPP_DEPRECATED _LIBCPP_NODEBUG = void;
-using __use_standard_header_cstdbool _LIBCPP_NODEBUG                = __standard_header_cstdbool;
-
+#  if _LIBCPP_STD_VER >= 17 && _LIBCPP_DIAGNOSE_DEPRECATED_HEADERS
+#    warning <cstdbool> is removed in C++20.
 #  endif
+
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
 
 #endif // _LIBCPP_CSTDBOOL
diff --git a/libcxx/include/ctgmath b/libcxx/include/ctgmath
index db0786f1e2c46..9a0049a38880f 100644
--- a/libcxx/include/ctgmath
+++ b/libcxx/include/ctgmath
@@ -28,17 +28,8 @@
 #    pragma GCC system_header
 #  endif
 
-#  if _LIBCPP_STD_VER >= 20
-
-using __standard_header_ctgmath
-    _LIBCPP_DEPRECATED_("removed in C++20. Include <cmath> and <complex> instead.") _LIBCPP_NODEBUG = void;
-using __use_standard_header_ctgmath _LIBCPP_NODEBUG = __standard_header_ctgmath;
-
-#  elif _LIBCPP_STD_VER >= 17
-
-using __standard_header_ctgmath _LIBCPP_DEPRECATED_("Include <cmath> and <complex> instead.") _LIBCPP_NODEBUG = void;
-using __use_standard_header_ctgmath _LIBCPP_NODEBUG = __standard_header_ctgmath;
-
+#  if _LIBCPP_STD_VER >= 17 && _LIBCPP_DIAGNOSE_DEPRECATED_HEADERS
+#    warning <ctgmath> is removed in C++20. Include <cmath> and <complex> instead.
 #  endif
 
 #endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
diff --git a/libcxx/test/extensions/clang/clang_modules_include.gen.py b/libcxx/test/extensions/clang/clang_modules_include.gen.py
index 28661049d6e85..f21c2cc9fd805 100644
--- a/libcxx/test/extensions/clang/clang_modules_include.gen.py
+++ b/libcxx/test/extensions/clang/clang_modules_include.gen.py
@@ -50,7 +50,7 @@
     print(
         f"""\
 //--- {header}.compile.pass.cpp
-// RUN: %{{cxx}} %s %{{flags}} %{{compile_flags}} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only
+// RUN: %{{cxx}} %s %{{flags}} %{{compile_flags}} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -Wno-deprecated
 
 {lit_header_restrictions.get(header, '')}
 {lit_header_undeprecations.get(header, '')}
@@ -62,7 +62,7 @@
 print(
     f"""\
 //--- import_std.compile.pass.mm
-// RUN: %{{cxx}} %s %{{flags}} %{{compile_flags}} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only
+// RUN: %{{cxx}} %s %{{flags}} %{{compile_flags}} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -Wno-deprecated
 
 // REQUIRES: clang-modules-build
 
diff --git a/libcxx/test/libcxx/transitive_includes.gen.py b/libcxx/test/libcxx/transitive_includes.gen.py
index 6ed35af7e275e..2b643e1f2ad48 100644
--- a/libcxx/test/libcxx/transitive_includes.gen.py
+++ b/libcxx/test/libcxx/transitive_includes.gen.py
@@ -89,7 +89,7 @@
 // UNSUPPORTED: LIBCXX-FREEBSD-FIXME
 
 // RUN: mkdir %t
-// RUN: %{{cxx}} %s %{{flags}} %{{compile_flags}} --trace-includes -fshow-skipped-includes --preprocess > /dev/null 2> %t/trace-includes.txt
+// RUN: %{{cxx}} %s %{{flags}} %{{compile_flags}} -Wno-deprecated --trace-includes -fshow-skipped-includes --preprocess > /dev/null 2> %t/trace-includes.txt
 // RUN: %{{python}} %{{libcxx-dir}}/test/libcxx/transitive_includes/to_csv.py %t/trace-includes.txt > %t/actual_transitive_includes.csv
 // RUN: cat %{{libcxx-dir}}/test/libcxx/transitive_includes/%{{cxx_std}}.csv | awk '/^{escaped_header} / {{ print }}' > %t/expected_transitive_includes.csv
 // RUN: diff -w %t/expected_transitive_includes.csv %t/actual_transitive_includes.csv
diff --git a/libcxx/test/std/depr/depr.cpp.headers/ccomplex.verify.cpp b/libcxx/test/std/depr/depr.cpp.headers/ccomplex.verify.cpp
index 0eaf82ce5cef0..f63c971f9592f 100644
--- a/libcxx/test/std/depr/depr.cpp.headers/ccomplex.verify.cpp
+++ b/libcxx/test/std/depr/depr.cpp.headers/ccomplex.verify.cpp
@@ -14,12 +14,6 @@
 // UNSUPPORTED: c++03, c++11, c++14
 // UNSUPPORTED: clang-modules-build
 
-#include "test_macros.h"
-
 #include <ccomplex>
 
-#if TEST_STD_VER >= 20
-// expected-warning@ccomplex:* {{'__standard_header_ccomplex' is deprecated: removed in C++20. Include <complex> instead.}}
-#else
-// expected-warning@ccomplex:* {{'__standard_header_ccomplex' is deprecated: Include <complex> instead.}}
-#endif
+// expected-warning@ccomplex:* {{<ccomplex> is removed in C++20. Include <complex> instead.}}
diff --git a/libcxx/test/std/depr/depr.cpp.headers/ciso646.verify.cpp b/libcxx/test/std/depr/depr.cpp.headers/ciso646.verify.cpp
index 04acd10081548..32b57033331c8 100644
--- a/libcxx/test/std/depr/depr.cpp.headers/ciso646.verify.cpp
+++ b/libcxx/test/std/depr/depr.cpp.headers/ciso646.verify.cpp
@@ -15,4 +15,5 @@
 // UNSUPPORTED: clang-modules-build
 
 #include <ciso646>
-// expected-warning@ciso646:* {{'__standard_header_ciso646' is deprecated: removed in C++20. Include <version> instead.}}
+
+// expected-warning@ciso646:* {{<ciso646> is removed in C++20. Include <version> instead.}}
diff --git a/libcxx/test/std/depr/depr.cpp.headers/cstdalign.verify.cpp b/libcxx/test/std/depr/depr.cpp.headers/cstdalign.verify.cpp
index dc9f1af55b3f1..258e82cfe0ad2 100644
--- a/libcxx/test/std/depr/depr.cpp.headers/cstdalign.verify.cpp
+++ b/libcxx/test/std/depr/depr.cpp.headers/cstdalign.verify.cpp
@@ -14,12 +14,6 @@
 // UNSUPPORTED: c++03, c++11, c++14
 // UNSUPPORTED: clang-modules-build
 
-#include "test_macros.h"
-
 #include <cstdalign>
 
-#if TEST_STD_VER >= 20
-// expected-warning@cstdalign:* {{'__standard_header_cstdalign' is deprecated: removed in C++20.}}
-#else
-// expected-warning@cstdalign:* {{'__standard_header_cstdalign' is deprecated}}
-#endif
+// expected-warning@cstdalign:* {{<cstdalign> is removed in C++20.}}
diff --git a/libcxx/test/std/depr/depr.cpp.headers/cstdbool.verify.cpp b/libcxx/test/std/depr/depr.cpp.headers/cstdbool.verify.cpp
index eddefe14d35ea..5c89cfad27c3d 100644
--- a/libcxx/test/std/depr/depr.cpp.headers/cstdbool.verify.cpp
+++ b/libcxx/test/std/depr/depr.cpp.headers/cstdbool.verify.cpp
@@ -14,12 +14,6 @@
 // UNSUPPORTED: c++03, c++11, c++14
 // UNSUPPORTED: clang-modules-build
 
-#include "test_macros.h"
-
 #include <cstdbool>
 
-#if TEST_STD_VER >= 20
-// expected-warning@cstdbool:* {{'__standard_header_cstdbool' is deprecated: removed in C++20.}}
-#else
-// expected-warning@cstdbool:* {{'__standard_header_cstdbool' is deprecated}}
-#endif
+// expected-warning@cstdbool:* {{<cstdbool> is removed in C++20.}}
diff --git a/libcxx/test/std/depr/depr.cpp.headers/ctgmath.verify.cpp b/libcxx/test/std/depr/depr.cpp.headers/ctgmath.verify.cpp
index 097ab1643d15a..1ada3768f894d 100644
--- a/libcxx/test/std/depr/depr.cpp.headers/ctgmath.verify.cpp
+++ b/libcxx/test/std/depr/depr.cpp.headers/ctgmath.verify.cpp
@@ -14,12 +14,6 @@
 // UNSUPPORTED: c++03, c++11, c++14
 // UNSUPPORTED: clang-modules-build
 
-#include "test_macros.h"
-
 #include <ctgmath>
 
-#if TEST_STD_VER >= 20
-// expected-warning@ctgmath:* {{'__standard_header_ctgmath' is deprecated: removed in C++20. Include <cmath> and <complex> instead.}}
-#else
-// expected-warning@ctgmath:* {{'__standard_header_ctgmath' is deprecated: Include <cmath> and <complex> instead.}}
-#endif
+// expected-warning@ctgmath:* {{<ctgmath> is removed in C++20. Include <cmath> and <complex> instead.}}