diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 2eff42918886c4..2a34aa4fe55cca 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -178,7 +178,7 @@ Status
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_atomic_lock_free_type_aliases``                ``201907L``
     ---------------------------------------------------------- -----------------
-    ``__cpp_lib_atomic_ref``                                   *unimplemented*
+    ``__cpp_lib_atomic_ref``                                   ``201806L``
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_atomic_shared_ptr``                            *unimplemented*
     ---------------------------------------------------------- -----------------
diff --git a/libcxx/include/version b/libcxx/include/version
index 460af8b6d396c3..21231a4d4b0fc8 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -366,7 +366,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 # define __cpp_lib_atomic_flag_test                     201907L
 // # define __cpp_lib_atomic_float                         201711L
 # define __cpp_lib_atomic_lock_free_type_aliases        201907L
-// # define __cpp_lib_atomic_ref                           201806L
+# define __cpp_lib_atomic_ref                           201806L
 // # define __cpp_lib_atomic_shared_ptr                    201711L
 # define __cpp_lib_atomic_value_initialization          201911L
 # if _LIBCPP_AVAILABILITY_HAS_SYNC
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp
index c907b7d840e30d..9ed18fbfe19ac4 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.compile.pass.cpp
@@ -200,17 +200,11 @@
 #   error "__cpp_lib_atomic_min_max should not be defined before c++26"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should be defined in c++20"
-#   endif
-#   if __cpp_lib_atomic_ref != 201806L
-#     error "__cpp_lib_atomic_ref should have the value 201806L in c++20"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_atomic_ref
+#   error "__cpp_lib_atomic_ref should be defined in c++20"
+# endif
+# if __cpp_lib_atomic_ref != 201806L
+#   error "__cpp_lib_atomic_ref should have the value 201806L in c++20"
 # endif
 
 # if !defined(_LIBCPP_VERSION)
@@ -299,17 +293,11 @@
 #   error "__cpp_lib_atomic_min_max should not be defined before c++26"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should be defined in c++23"
-#   endif
-#   if __cpp_lib_atomic_ref != 201806L
-#     error "__cpp_lib_atomic_ref should have the value 201806L in c++23"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_atomic_ref
+#   error "__cpp_lib_atomic_ref should be defined in c++23"
+# endif
+# if __cpp_lib_atomic_ref != 201806L
+#   error "__cpp_lib_atomic_ref should have the value 201806L in c++23"
 # endif
 
 # if !defined(_LIBCPP_VERSION)
@@ -407,17 +395,11 @@
 #   endif
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should be defined in c++26"
-#   endif
-#   if __cpp_lib_atomic_ref != 201806L
-#     error "__cpp_lib_atomic_ref should have the value 201806L in c++26"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_atomic_ref
+#   error "__cpp_lib_atomic_ref should be defined in c++26"
+# endif
+# if __cpp_lib_atomic_ref != 201806L
+#   error "__cpp_lib_atomic_ref should have the value 201806L in c++26"
 # endif
 
 # if !defined(_LIBCPP_VERSION)
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
index 9a5a10a8fb0f5a..c0ffd78ebe3b15 100644
--- 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
@@ -3254,17 +3254,11 @@
 #   error "__cpp_lib_atomic_min_max should not be defined before c++26"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should be defined in c++20"
-#   endif
-#   if __cpp_lib_atomic_ref != 201806L
-#     error "__cpp_lib_atomic_ref should have the value 201806L in c++20"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_atomic_ref
+#   error "__cpp_lib_atomic_ref should be defined in c++20"
+# endif
+# if __cpp_lib_atomic_ref != 201806L
+#   error "__cpp_lib_atomic_ref should have the value 201806L in c++20"
 # endif
 
 # if !defined(_LIBCPP_VERSION)
@@ -4675,17 +4669,11 @@
 #   error "__cpp_lib_atomic_min_max should not be defined before c++26"
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should be defined in c++23"
-#   endif
-#   if __cpp_lib_atomic_ref != 201806L
-#     error "__cpp_lib_atomic_ref should have the value 201806L in c++23"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_atomic_ref
+#   error "__cpp_lib_atomic_ref should be defined in c++23"
+# endif
+# if __cpp_lib_atomic_ref != 201806L
+#   error "__cpp_lib_atomic_ref should have the value 201806L in c++23"
 # endif
 
 # if !defined(_LIBCPP_VERSION)
@@ -6318,17 +6306,11 @@
 #   endif
 # endif
 
-# if !defined(_LIBCPP_VERSION)
-#   ifndef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should be defined in c++26"
-#   endif
-#   if __cpp_lib_atomic_ref != 201806L
-#     error "__cpp_lib_atomic_ref should have the value 201806L in c++26"
-#   endif
-# else // _LIBCPP_VERSION
-#   ifdef __cpp_lib_atomic_ref
-#     error "__cpp_lib_atomic_ref should not be defined because it is unimplemented in libc++!"
-#   endif
+# ifndef __cpp_lib_atomic_ref
+#   error "__cpp_lib_atomic_ref should be defined in c++26"
+# endif
+# if __cpp_lib_atomic_ref != 201806L
+#   error "__cpp_lib_atomic_ref should have the value 201806L in c++26"
 # endif
 
 # if !defined(_LIBCPP_VERSION)
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index d79892e140ebd4..e92b6613b11a89 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -184,7 +184,6 @@ def add_version_header(tc):
             "name": "__cpp_lib_atomic_ref",
             "values": {"c++20": 201806},
             "headers": ["atomic"],
-            "unimplemented": True,
         },
         {
             "name": "__cpp_lib_atomic_shared_ptr",