diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -222,7 +222,7 @@
     ------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_utility``                   ``201811L``
     ------------------------------------------------- -----------------
-    ``__cpp_lib_constexpr_vector``                    *unimplemented*
+    ``__cpp_lib_constexpr_vector``                    ``201907L``
     ------------------------------------------------- -----------------
     ``__cpp_lib_coroutine``                           ``201902L``
     ------------------------------------------------- -----------------
diff --git a/libcxx/include/version b/libcxx/include/version
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -326,7 +326,7 @@
 # define __cpp_lib_constexpr_string_view                201811L
 # define __cpp_lib_constexpr_tuple                      201811L
 # define __cpp_lib_constexpr_utility                    201811L
-// # define __cpp_lib_constexpr_vector                     201907L
+# define __cpp_lib_constexpr_vector                     201907L
 # define __cpp_lib_coroutine                            201902L
 # if _LIBCPP_STD_VER > 17 && defined(__cpp_impl_destroying_delete) && __cpp_impl_destroying_delete >= 201806L
 #   define __cpp_lib_destroying_delete                  201806L
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.compile.pass.cpp
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.compile.pass.cpp
@@ -123,17 +123,11 @@
 #   error "__cpp_lib_allocator_traits_is_always_equal should have the value 201411L in c++20"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should be defined in c++20"
-#   endif
-#   if __cpp_lib_constexpr_vector != 201907L
-#     error "__cpp_lib_constexpr_vector should have the value 201907L in c++20"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_constexpr_vector
+#   error "__cpp_lib_constexpr_vector should be defined in c++20"
+# endif
+# if __cpp_lib_constexpr_vector != 201907L
+#   error "__cpp_lib_constexpr_vector should have the value 201907L in c++20"
 # endif
 
 # ifndef __cpp_lib_erase_if
@@ -170,17 +164,11 @@
 #   error "__cpp_lib_allocator_traits_is_always_equal should have the value 201411L in c++2b"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should be defined in c++2b"
-#   endif
-#   if __cpp_lib_constexpr_vector != 201907L
-#     error "__cpp_lib_constexpr_vector should have the value 201907L in c++2b"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_constexpr_vector
+#   error "__cpp_lib_constexpr_vector should be defined in c++2b"
+# endif
+# if __cpp_lib_constexpr_vector != 201907L
+#   error "__cpp_lib_constexpr_vector should have the value 201907L in c++2b"
 # endif
 
 # ifndef __cpp_lib_erase_if
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -2772,17 +2772,11 @@
 #   error "__cpp_lib_constexpr_utility should have the value 201811L in c++20"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should be defined in c++20"
-#   endif
-#   if __cpp_lib_constexpr_vector != 201907L
-#     error "__cpp_lib_constexpr_vector should have the value 201907L in c++20"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_constexpr_vector
+#   error "__cpp_lib_constexpr_vector should be defined in c++20"
+# endif
+# if __cpp_lib_constexpr_vector != 201907L
+#   error "__cpp_lib_constexpr_vector should have the value 201907L in c++20"
 # endif
 
 # ifndef __cpp_lib_coroutine
@@ -4015,17 +4009,11 @@
 #   error "__cpp_lib_constexpr_utility should have the value 201811L in c++2b"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should be defined in c++2b"
-#   endif
-#   if __cpp_lib_constexpr_vector != 201907L
-#     error "__cpp_lib_constexpr_vector should have the value 201907L in c++2b"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_constexpr_vector
-#     error "__cpp_lib_constexpr_vector should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_constexpr_vector
+#   error "__cpp_lib_constexpr_vector should be defined in c++2b"
+# endif
+# if __cpp_lib_constexpr_vector != 201907L
+#   error "__cpp_lib_constexpr_vector should have the value 201907L in c++2b"
 # endif
 
 # ifndef __cpp_lib_coroutine
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
@@ -277,7 +277,6 @@
     "name": "__cpp_lib_constexpr_vector",
     "values": { "c++20": 201907 },
     "headers": ["vector"],
-    "unimplemented": True,
   }, {
     "name": "__cpp_lib_coroutine",
     "values": { "c++20": 201902 },