diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -1292,10 +1292,6 @@
 #define _LIBCPP_HAS_NO_BUILTIN_ADDRESSOF
 #endif
 
-#if !__has_builtin(__builtin_is_constant_evaluated) && _GNUC_VER < 900
-#define _LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED
-#endif
-
 #if __has_attribute(diagnose_if) && !defined(_LIBCPP_DISABLE_ADDITIONAL_DIAGNOSTICS)
 #  define _LIBCPP_DIAGNOSE_WARNING(...) \
      __attribute__((diagnose_if(__VA_ARGS__, "warning")))
diff --git a/libcxx/include/__format/format_parse_context.h b/libcxx/include/__format/format_parse_context.h
--- a/libcxx/include/__format/format_parse_context.h
+++ b/libcxx/include/__format/format_parse_context.h
@@ -29,8 +29,7 @@
 // If the compiler has no concepts support, the format header will be disabled.
 // Without concepts support enable_if needs to be used and that too much effort
 // to support compilers with partial C++20 support.
-#if !defined(_LIBCPP_HAS_NO_CONCEPTS) &&                                       \
-    !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED)
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
 
 template <class _CharT>
 class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT basic_format_parse_context {
@@ -102,7 +101,7 @@
 using format_parse_context = basic_format_parse_context<char>;
 using wformat_parse_context = basic_format_parse_context<wchar_t>;
 
-#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED)
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
 
 #endif //_LIBCPP_STD_VER > 17
 
diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -4453,7 +4453,6 @@
 struct __can_extract_map_key<_ValTy, _Key, _Key, _RawValTy>
     : false_type {};
 
-#ifndef _LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED
 #if _LIBCPP_STD_VER > 17
 _LIBCPP_INLINE_VISIBILITY
 inline constexpr bool is_constant_evaluated() noexcept {
@@ -4463,10 +4462,6 @@
 
 inline _LIBCPP_CONSTEXPR
 bool __libcpp_is_constant_evaluated() _NOEXCEPT { return __builtin_is_constant_evaluated(); }
-#else
-inline _LIBCPP_CONSTEXPR
-bool __libcpp_is_constant_evaluated() _NOEXCEPT { return false; }
-#endif
 
 template <class _CharT>
 using _IsCharLikeType = _And<is_standard_layout<_CharT>, is_trivial<_CharT> >;
diff --git a/libcxx/include/version b/libcxx/include/version
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -328,9 +328,7 @@
 #   define __cpp_lib_integer_comparison_functions       202002L
 # endif
 # define __cpp_lib_interpolate                          201902L
-# if !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED)
-#   define __cpp_lib_is_constant_evaluated              201811L
-# endif
+# define __cpp_lib_is_constant_evaluated                201811L
 // # define __cpp_lib_is_layout_compatible                 201907L
 # define __cpp_lib_is_nothrow_convertible               201806L
 // # define __cpp_lib_is_pointer_interconvertible          201907L
diff --git a/libcxx/test/libcxx/type_traits/is_constant_evaluated.pass.cpp b/libcxx/test/libcxx/type_traits/is_constant_evaluated.pass.cpp
--- a/libcxx/test/libcxx/type_traits/is_constant_evaluated.pass.cpp
+++ b/libcxx/test/libcxx/type_traits/is_constant_evaluated.pass.cpp
@@ -23,7 +23,7 @@
     ASSERT_SAME_TYPE(decltype(std::__libcpp_is_constant_evaluated()), bool);
     ASSERT_NOEXCEPT(std::__libcpp_is_constant_evaluated());
 
-#if !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED) && !defined(_LIBCPP_CXX03_LANG)
+#if !defined(_LIBCPP_CXX03_LANG)
     static_assert(std::__libcpp_is_constant_evaluated(), "");
 #endif
 
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp
@@ -402,17 +402,11 @@
 #   endif
 # endif
 
-# if TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900
-#   ifndef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should be defined in c++20"
-#   endif
-#   if __cpp_lib_is_constant_evaluated != 201811L
-#     error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++20"
-#   endif
-# else
-#   ifdef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should not be defined when TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900 is not defined!"
-#   endif
+# ifndef __cpp_lib_is_constant_evaluated
+#   error "__cpp_lib_is_constant_evaluated should be defined in c++20"
+# endif
+# if __cpp_lib_is_constant_evaluated != 201811L
+#   error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++20"
 # endif
 
 # ifndef __cpp_lib_is_final
@@ -571,17 +565,11 @@
 #   endif
 # endif
 
-# if TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900
-#   ifndef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should be defined in c++2b"
-#   endif
-#   if __cpp_lib_is_constant_evaluated != 201811L
-#     error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++2b"
-#   endif
-# else
-#   ifdef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should not be defined when TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900 is not defined!"
-#   endif
+# ifndef __cpp_lib_is_constant_evaluated
+#   error "__cpp_lib_is_constant_evaluated should be defined in c++2b"
+# endif
+# if __cpp_lib_is_constant_evaluated != 201811L
+#   error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++2b"
 # endif
 
 # ifndef __cpp_lib_is_final
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
@@ -2707,17 +2707,11 @@
 #   endif
 # endif
 
-# if TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900
-#   ifndef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should be defined in c++20"
-#   endif
-#   if __cpp_lib_is_constant_evaluated != 201811L
-#     error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++20"
-#   endif
-# else
-#   ifdef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should not be defined when TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900 is not defined!"
-#   endif
+# ifndef __cpp_lib_is_constant_evaluated
+#   error "__cpp_lib_is_constant_evaluated should be defined in c++20"
+# endif
+# if __cpp_lib_is_constant_evaluated != 201811L
+#   error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++20"
 # endif
 
 # ifndef __cpp_lib_is_final
@@ -3888,17 +3882,11 @@
 #   endif
 # endif
 
-# if TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900
-#   ifndef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should be defined in c++2b"
-#   endif
-#   if __cpp_lib_is_constant_evaluated != 201811L
-#     error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++2b"
-#   endif
-# else
-#   ifdef __cpp_lib_is_constant_evaluated
-#     error "__cpp_lib_is_constant_evaluated should not be defined when TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900 is not defined!"
-#   endif
+# ifndef __cpp_lib_is_constant_evaluated
+#   error "__cpp_lib_is_constant_evaluated should be defined in c++2b"
+# endif
+# if __cpp_lib_is_constant_evaluated != 201811L
+#   error "__cpp_lib_is_constant_evaluated should have the value 201811L in c++2b"
 # endif
 
 # ifndef __cpp_lib_is_final
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -369,8 +369,6 @@
     "name": "__cpp_lib_is_constant_evaluated",
     "values": { "c++20": 201811 },
     "headers": ["type_traits"],
-    "test_suite_guard": "TEST_HAS_BUILTIN(__builtin_is_constant_evaluated) || TEST_GCC_VER >= 900",
-    "libcxx_guard": "!defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED)",
   }, {
     "name": "__cpp_lib_is_final",
     "values": { "c++14": 201402 },