diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -916,6 +916,7 @@
   numbers
   numeric
   optional
+  optional_formatter
   ostream
   queue
   random
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1245,6 +1245,10 @@
     header "optional"
     export *
   }
+  module optional_formatter {
+    header "optional_formatter"
+    export *
+  }
   module ostream {
     @requires_LIBCXX_ENABLE_LOCALIZATION@
     header "ostream"
diff --git a/libcxx/include/optional_formatter b/libcxx/include/optional_formatter
new file mode 100644
--- /dev/null
+++ b/libcxx/include/optional_formatter
@@ -0,0 +1,67 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_OPTIONAL_FORMATTER
+#define _LIBCPP_OPTIONAL_FORMATTER
+
+#include <__config>
+#include <__format/concepts.h>
+#include <__format/format_error.h>
+#include <__format/format_parse_context.h>
+#include <__format/formatter.h>
+#include <__format/formatter_bool.h>
+#include <__format/formatter_integer.h>
+#include <__format/formatter_integral.h>
+#include <__format/formatter_pointer.h>
+#include <__format/formatter_string.h>
+#include <__format/formatter_tuple.h>
+#include <__format/parser_std_format_spec.h>
+#include <concepts>
+#include <optional>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 20
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp, __fmt_char_type _CharT>
+  requires same_as<_Tp, optional<typename _Tp::value_type>>
+struct _LIBCPP_TEMPLATE_VIS formatter<_Tp, _CharT> {
+  formatter<typename _Tp::value_type, _CharT> __underlying_;
+
+  template <class _ParseContext>
+  _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator parse(_ParseContext& __ctx) {
+    return __parser_.__parse(__ctx, __format_spec::__fields_integral); // random value
+  }
+
+  template <class _FormatContext>
+  typename _FormatContext::iterator _LIBCPP_HIDE_FROM_ABI format(_Tp __value, _FormatContext& __ctx) const {
+    auto __out_it = __ctx.out();
+    *__out_it++   = _CharT('[');
+    if (__value.has_value()) {
+      __ctx.advance_to(__out_it);
+      __underlying_.format(*__value, __ctx);
+      __out_it = __ctx.out();
+    }
+
+    *__out_it++ = _CharT(']');
+    return __out_it;
+  }
+
+  __format_spec::__parser<_CharT> __parser_;
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 20
+
+#endif // _LIBCPP_OPTIONAL_FORMATTER
diff --git a/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp b/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
--- a/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
+++ b/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
@@ -459,289 +459,295 @@
 #endif
 
 // RUN: %{build} -DTEST_78
-#if defined(TEST_78) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#   include <ostream>
+#if defined(TEST_78)
+#   include <optional_formatter>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_79
-#if defined(TEST_79)
-#   include <queue>
+#if defined(TEST_79) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#   include <ostream>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_80
 #if defined(TEST_80)
-#   include <random>
+#   include <queue>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_81
 #if defined(TEST_81)
-#   include <ranges>
+#   include <random>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_82
 #if defined(TEST_82)
-#   include <ratio>
+#   include <ranges>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_83
-#if defined(TEST_83) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#   include <regex>
+#if defined(TEST_83)
+#   include <ratio>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_84
-#if defined(TEST_84)
-#   include <scoped_allocator>
+#if defined(TEST_84) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#   include <regex>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_85
-#if defined(TEST_85) && !defined(_LIBCPP_HAS_NO_THREADS)
-#   include <semaphore>
+#if defined(TEST_85)
+#   include <scoped_allocator>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_86
-#if defined(TEST_86)
-#   include <set>
+#if defined(TEST_86) && !defined(_LIBCPP_HAS_NO_THREADS)
+#   include <semaphore>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_88
-#if defined(TEST_88) && !defined(_LIBCPP_HAS_NO_THREADS)
-#   include <shared_mutex>
+// RUN: %{build} -DTEST_87
+#if defined(TEST_87)
+#   include <set>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_89
-#if defined(TEST_89)
-#   include <source_location>
+#if defined(TEST_89) && !defined(_LIBCPP_HAS_NO_THREADS)
+#   include <shared_mutex>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_90
 #if defined(TEST_90)
-#   include <span>
+#   include <source_location>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_91
-#if defined(TEST_91) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#   include <sstream>
+#if defined(TEST_91)
+#   include <span>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_92
-#if defined(TEST_92)
+#if defined(TEST_92) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#   include <sstream>
+    using HandlerType = decltype(std::__libcpp_verbose_abort);
+#endif
+
+// RUN: %{build} -DTEST_93
+#if defined(TEST_93)
 #   include <stack>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_96
-#if defined(TEST_96)
+// RUN: %{build} -DTEST_97
+#if defined(TEST_97)
 #   include <stdexcept>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_100
-#if defined(TEST_100) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+// RUN: %{build} -DTEST_101
+#if defined(TEST_101) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #   include <streambuf>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_101
-#if defined(TEST_101)
+// RUN: %{build} -DTEST_102
+#if defined(TEST_102)
 #   include <string>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_103
-#if defined(TEST_103)
+// RUN: %{build} -DTEST_104
+#if defined(TEST_104)
 #   include <string_view>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_104
-#if defined(TEST_104) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+// RUN: %{build} -DTEST_105
+#if defined(TEST_105) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #   include <strstream>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_105
-#if defined(TEST_105)
+// RUN: %{build} -DTEST_106
+#if defined(TEST_106)
 #   include <system_error>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_107
-#if defined(TEST_107) && !defined(_LIBCPP_HAS_NO_THREADS)
-#   include <thread>
-    using HandlerType = decltype(std::__libcpp_verbose_abort);
-#endif
-
 // RUN: %{build} -DTEST_108
-#if defined(TEST_108)
-#   include <tuple>
+#if defined(TEST_108) && !defined(_LIBCPP_HAS_NO_THREADS)
+#   include <thread>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_109
 #if defined(TEST_109)
-#   include <type_traits>
+#   include <tuple>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_110
 #if defined(TEST_110)
-#   include <typeindex>
+#   include <type_traits>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_111
 #if defined(TEST_111)
-#   include <typeinfo>
+#   include <typeindex>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_113
-#if defined(TEST_113)
-#   include <unordered_map>
+// RUN: %{build} -DTEST_112
+#if defined(TEST_112)
+#   include <typeinfo>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_114
 #if defined(TEST_114)
-#   include <unordered_set>
+#   include <unordered_map>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_115
 #if defined(TEST_115)
-#   include <utility>
+#   include <unordered_set>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_116
 #if defined(TEST_116)
-#   include <valarray>
+#   include <utility>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_117
 #if defined(TEST_117)
-#   include <variant>
+#   include <valarray>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_118
 #if defined(TEST_118)
-#   include <vector>
+#   include <variant>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_119
 #if defined(TEST_119)
-#   include <version>
+#   include <vector>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
-// RUN: %{build} -DTEST_122
-#if defined(TEST_122) && __cplusplus >= 201103L
-#   include <experimental/deque>
+// RUN: %{build} -DTEST_120
+#if defined(TEST_120)
+#   include <version>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_123
 #if defined(TEST_123) && __cplusplus >= 201103L
-#   include <experimental/forward_list>
+#   include <experimental/deque>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_124
 #if defined(TEST_124) && __cplusplus >= 201103L
-#   include <experimental/iterator>
+#   include <experimental/forward_list>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_125
 #if defined(TEST_125) && __cplusplus >= 201103L
-#   include <experimental/list>
+#   include <experimental/iterator>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_126
 #if defined(TEST_126) && __cplusplus >= 201103L
-#   include <experimental/map>
+#   include <experimental/list>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_127
 #if defined(TEST_127) && __cplusplus >= 201103L
-#   include <experimental/memory_resource>
+#   include <experimental/map>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_128
 #if defined(TEST_128) && __cplusplus >= 201103L
-#   include <experimental/propagate_const>
+#   include <experimental/memory_resource>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_129
-#if defined(TEST_129) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && __cplusplus >= 201103L
-#   include <experimental/regex>
+#if defined(TEST_129) && __cplusplus >= 201103L
+#   include <experimental/propagate_const>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_130
-#if defined(TEST_130) && __cplusplus >= 201103L
-#   include <experimental/set>
+#if defined(TEST_130) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && __cplusplus >= 201103L
+#   include <experimental/regex>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_131
 #if defined(TEST_131) && __cplusplus >= 201103L
-#   include <experimental/simd>
+#   include <experimental/set>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_132
 #if defined(TEST_132) && __cplusplus >= 201103L
-#   include <experimental/string>
+#   include <experimental/simd>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_133
 #if defined(TEST_133) && __cplusplus >= 201103L
-#   include <experimental/type_traits>
+#   include <experimental/string>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_134
 #if defined(TEST_134) && __cplusplus >= 201103L
-#   include <experimental/unordered_map>
+#   include <experimental/type_traits>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_135
 #if defined(TEST_135) && __cplusplus >= 201103L
-#   include <experimental/unordered_set>
+#   include <experimental/unordered_map>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_136
 #if defined(TEST_136) && __cplusplus >= 201103L
-#   include <experimental/utility>
+#   include <experimental/unordered_set>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
 
 // RUN: %{build} -DTEST_137
 #if defined(TEST_137) && __cplusplus >= 201103L
+#   include <experimental/utility>
+    using HandlerType = decltype(std::__libcpp_verbose_abort);
+#endif
+
+// RUN: %{build} -DTEST_138
+#if defined(TEST_138) && __cplusplus >= 201103L
 #   include <experimental/vector>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
diff --git a/libcxx/test/libcxx/clang_tidy.sh.cpp b/libcxx/test/libcxx/clang_tidy.sh.cpp
--- a/libcxx/test/libcxx/clang_tidy.sh.cpp
+++ b/libcxx/test/libcxx/clang_tidy.sh.cpp
@@ -143,6 +143,7 @@
 #include <numbers>
 #include <numeric>
 #include <optional>
+#include <optional_formatter>
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #   include <ostream>
 #endif
diff --git a/libcxx/test/libcxx/double_include.sh.cpp b/libcxx/test/libcxx/double_include.sh.cpp
--- a/libcxx/test/libcxx/double_include.sh.cpp
+++ b/libcxx/test/libcxx/double_include.sh.cpp
@@ -141,6 +141,7 @@
 #include <numbers>
 #include <numeric>
 #include <optional>
+#include <optional_formatter>
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #   include <ostream>
 #endif
diff --git a/libcxx/test/libcxx/min_max_macros.compile.pass.cpp b/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
--- a/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
+++ b/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
@@ -219,6 +219,8 @@
 TEST_MACROS();
 #include <optional>
 TEST_MACROS();
+#include <optional_formatter>
+TEST_MACROS();
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #   include <ostream>
 TEST_MACROS();
diff --git a/libcxx/test/libcxx/modules_include.sh.cpp b/libcxx/test/libcxx/modules_include.sh.cpp
--- a/libcxx/test/libcxx/modules_include.sh.cpp
+++ b/libcxx/test/libcxx/modules_include.sh.cpp
@@ -506,364 +506,369 @@
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_78 &' >> %t.sh
 // RUN: echo 'TEST_78=$!' >> %t.sh
 // RUN: echo "wait $TEST_62" >> %t.sh
-#if defined(TEST_78) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#include <ostream>
+#if defined(TEST_78)
+#include <optional_formatter>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_79 &' >> %t.sh
 // RUN: echo 'TEST_79=$!' >> %t.sh
 // RUN: echo "wait $TEST_63" >> %t.sh
-#if defined(TEST_79)
-#include <queue>
+#if defined(TEST_79) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <ostream>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_80 &' >> %t.sh
 // RUN: echo 'TEST_80=$!' >> %t.sh
 // RUN: echo "wait $TEST_64" >> %t.sh
 #if defined(TEST_80)
-#include <random>
+#include <queue>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_81 &' >> %t.sh
 // RUN: echo 'TEST_81=$!' >> %t.sh
 // RUN: echo "wait $TEST_65" >> %t.sh
 #if defined(TEST_81)
-#include <ranges>
+#include <random>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_82 &' >> %t.sh
 // RUN: echo 'TEST_82=$!' >> %t.sh
 // RUN: echo "wait $TEST_66" >> %t.sh
 #if defined(TEST_82)
-#include <ratio>
+#include <ranges>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_83 &' >> %t.sh
 // RUN: echo 'TEST_83=$!' >> %t.sh
 // RUN: echo "wait $TEST_67" >> %t.sh
-#if defined(TEST_83) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#include <regex>
+#if defined(TEST_83)
+#include <ratio>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_84 &' >> %t.sh
 // RUN: echo 'TEST_84=$!' >> %t.sh
 // RUN: echo "wait $TEST_68" >> %t.sh
-#if defined(TEST_84)
-#include <scoped_allocator>
+#if defined(TEST_84) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <regex>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_85 &' >> %t.sh
 // RUN: echo 'TEST_85=$!' >> %t.sh
 // RUN: echo "wait $TEST_69" >> %t.sh
-#if defined(TEST_85) && !defined(_LIBCPP_HAS_NO_THREADS)
-#include <semaphore>
+#if defined(TEST_85)
+#include <scoped_allocator>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_86 &' >> %t.sh
 // RUN: echo 'TEST_86=$!' >> %t.sh
 // RUN: echo "wait $TEST_70" >> %t.sh
-#if defined(TEST_86)
-#include <set>
+#if defined(TEST_86) && !defined(_LIBCPP_HAS_NO_THREADS)
+#include <semaphore>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_87 &' >> %t.sh
 // RUN: echo 'TEST_87=$!' >> %t.sh
 // RUN: echo "wait $TEST_71" >> %t.sh
 #if defined(TEST_87)
-#include <setjmp.h>
+#include <set>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_88 &' >> %t.sh
 // RUN: echo 'TEST_88=$!' >> %t.sh
 // RUN: echo "wait $TEST_72" >> %t.sh
-#if defined(TEST_88) && !defined(_LIBCPP_HAS_NO_THREADS)
-#include <shared_mutex>
+#if defined(TEST_88)
+#include <setjmp.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_89 &' >> %t.sh
 // RUN: echo 'TEST_89=$!' >> %t.sh
 // RUN: echo "wait $TEST_73" >> %t.sh
-#if defined(TEST_89)
-#include <source_location>
+#if defined(TEST_89) && !defined(_LIBCPP_HAS_NO_THREADS)
+#include <shared_mutex>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_90 &' >> %t.sh
 // RUN: echo 'TEST_90=$!' >> %t.sh
 // RUN: echo "wait $TEST_74" >> %t.sh
 #if defined(TEST_90)
-#include <span>
+#include <source_location>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_91 &' >> %t.sh
 // RUN: echo 'TEST_91=$!' >> %t.sh
 // RUN: echo "wait $TEST_75" >> %t.sh
-#if defined(TEST_91) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#include <sstream>
+#if defined(TEST_91)
+#include <span>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_92 &' >> %t.sh
 // RUN: echo 'TEST_92=$!' >> %t.sh
 // RUN: echo "wait $TEST_76" >> %t.sh
-#if defined(TEST_92)
-#include <stack>
+#if defined(TEST_92) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <sstream>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_93 &' >> %t.sh
 // RUN: echo 'TEST_93=$!' >> %t.sh
 // RUN: echo "wait $TEST_77" >> %t.sh
-#if defined(TEST_93) && __cplusplus > 202002L && !defined(_LIBCPP_HAS_NO_THREADS)
-#include <stdatomic.h>
+#if defined(TEST_93)
+#include <stack>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_94 &' >> %t.sh
 // RUN: echo 'TEST_94=$!' >> %t.sh
 // RUN: echo "wait $TEST_78" >> %t.sh
-#if defined(TEST_94)
-#include <stdbool.h>
+#if defined(TEST_94) && __cplusplus > 202002L && !defined(_LIBCPP_HAS_NO_THREADS)
+#include <stdatomic.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_95 &' >> %t.sh
 // RUN: echo 'TEST_95=$!' >> %t.sh
 // RUN: echo "wait $TEST_79" >> %t.sh
 #if defined(TEST_95)
-#include <stddef.h>
+#include <stdbool.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_96 &' >> %t.sh
 // RUN: echo 'TEST_96=$!' >> %t.sh
 // RUN: echo "wait $TEST_80" >> %t.sh
 #if defined(TEST_96)
-#include <stdexcept>
+#include <stddef.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_97 &' >> %t.sh
 // RUN: echo 'TEST_97=$!' >> %t.sh
 // RUN: echo "wait $TEST_81" >> %t.sh
 #if defined(TEST_97)
-#include <stdint.h>
+#include <stdexcept>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_98 &' >> %t.sh
 // RUN: echo 'TEST_98=$!' >> %t.sh
 // RUN: echo "wait $TEST_82" >> %t.sh
 #if defined(TEST_98)
-#include <stdio.h>
+#include <stdint.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_99 &' >> %t.sh
 // RUN: echo 'TEST_99=$!' >> %t.sh
 // RUN: echo "wait $TEST_83" >> %t.sh
 #if defined(TEST_99)
-#include <stdlib.h>
+#include <stdio.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_100 &' >> %t.sh
 // RUN: echo 'TEST_100=$!' >> %t.sh
 // RUN: echo "wait $TEST_84" >> %t.sh
-#if defined(TEST_100) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#include <streambuf>
+#if defined(TEST_100)
+#include <stdlib.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_101 &' >> %t.sh
 // RUN: echo 'TEST_101=$!' >> %t.sh
 // RUN: echo "wait $TEST_85" >> %t.sh
-#if defined(TEST_101)
-#include <string>
+#if defined(TEST_101) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <streambuf>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_102 &' >> %t.sh
 // RUN: echo 'TEST_102=$!' >> %t.sh
 // RUN: echo "wait $TEST_86" >> %t.sh
 #if defined(TEST_102)
-#include <string.h>
+#include <string>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_103 &' >> %t.sh
 // RUN: echo 'TEST_103=$!' >> %t.sh
 // RUN: echo "wait $TEST_87" >> %t.sh
 #if defined(TEST_103)
-#include <string_view>
+#include <string.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_104 &' >> %t.sh
 // RUN: echo 'TEST_104=$!' >> %t.sh
 // RUN: echo "wait $TEST_88" >> %t.sh
-#if defined(TEST_104) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#include <strstream>
+#if defined(TEST_104)
+#include <string_view>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_105 &' >> %t.sh
 // RUN: echo 'TEST_105=$!' >> %t.sh
 // RUN: echo "wait $TEST_89" >> %t.sh
-#if defined(TEST_105)
-#include <system_error>
+#if defined(TEST_105) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <strstream>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_106 &' >> %t.sh
 // RUN: echo 'TEST_106=$!' >> %t.sh
 // RUN: echo "wait $TEST_90" >> %t.sh
 #if defined(TEST_106)
-#include <tgmath.h>
+#include <system_error>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_107 &' >> %t.sh
 // RUN: echo 'TEST_107=$!' >> %t.sh
 // RUN: echo "wait $TEST_91" >> %t.sh
-#if defined(TEST_107) && !defined(_LIBCPP_HAS_NO_THREADS)
-#include <thread>
+#if defined(TEST_107)
+#include <tgmath.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_108 &' >> %t.sh
 // RUN: echo 'TEST_108=$!' >> %t.sh
 // RUN: echo "wait $TEST_92" >> %t.sh
-#if defined(TEST_108)
-#include <tuple>
+#if defined(TEST_108) && !defined(_LIBCPP_HAS_NO_THREADS)
+#include <thread>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_109 &' >> %t.sh
 // RUN: echo 'TEST_109=$!' >> %t.sh
 // RUN: echo "wait $TEST_93" >> %t.sh
 #if defined(TEST_109)
-#include <type_traits>
+#include <tuple>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_110 &' >> %t.sh
 // RUN: echo 'TEST_110=$!' >> %t.sh
 // RUN: echo "wait $TEST_94" >> %t.sh
 #if defined(TEST_110)
-#include <typeindex>
+#include <type_traits>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_111 &' >> %t.sh
 // RUN: echo 'TEST_111=$!' >> %t.sh
 // RUN: echo "wait $TEST_95" >> %t.sh
 #if defined(TEST_111)
-#include <typeinfo>
+#include <typeindex>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_112 &' >> %t.sh
 // RUN: echo 'TEST_112=$!' >> %t.sh
 // RUN: echo "wait $TEST_96" >> %t.sh
 #if defined(TEST_112)
-#include <uchar.h>
+#include <typeinfo>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_113 &' >> %t.sh
 // RUN: echo 'TEST_113=$!' >> %t.sh
 // RUN: echo "wait $TEST_97" >> %t.sh
 #if defined(TEST_113)
-#include <unordered_map>
+#include <uchar.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_114 &' >> %t.sh
 // RUN: echo 'TEST_114=$!' >> %t.sh
 // RUN: echo "wait $TEST_98" >> %t.sh
 #if defined(TEST_114)
-#include <unordered_set>
+#include <unordered_map>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_115 &' >> %t.sh
 // RUN: echo 'TEST_115=$!' >> %t.sh
 // RUN: echo "wait $TEST_99" >> %t.sh
 #if defined(TEST_115)
-#include <utility>
+#include <unordered_set>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_116 &' >> %t.sh
 // RUN: echo 'TEST_116=$!' >> %t.sh
 // RUN: echo "wait $TEST_100" >> %t.sh
 #if defined(TEST_116)
-#include <valarray>
+#include <utility>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_117 &' >> %t.sh
 // RUN: echo 'TEST_117=$!' >> %t.sh
 // RUN: echo "wait $TEST_101" >> %t.sh
 #if defined(TEST_117)
-#include <variant>
+#include <valarray>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_118 &' >> %t.sh
 // RUN: echo 'TEST_118=$!' >> %t.sh
 // RUN: echo "wait $TEST_102" >> %t.sh
 #if defined(TEST_118)
-#include <vector>
+#include <variant>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_119 &' >> %t.sh
 // RUN: echo 'TEST_119=$!' >> %t.sh
 // RUN: echo "wait $TEST_103" >> %t.sh
 #if defined(TEST_119)
-#include <version>
+#include <vector>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_120 &' >> %t.sh
 // RUN: echo 'TEST_120=$!' >> %t.sh
 // RUN: echo "wait $TEST_104" >> %t.sh
-#if defined(TEST_120) && !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
-#include <wchar.h>
+#if defined(TEST_120)
+#include <version>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_121 &' >> %t.sh
 // RUN: echo 'TEST_121=$!' >> %t.sh
 // RUN: echo "wait $TEST_105" >> %t.sh
 #if defined(TEST_121) && !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
-#include <wctype.h>
+#include <wchar.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_122 &' >> %t.sh
 // RUN: echo 'TEST_122=$!' >> %t.sh
 // RUN: echo "wait $TEST_106" >> %t.sh
-#if defined(TEST_122) && __cplusplus >= 201103L
-#include <experimental/deque>
+#if defined(TEST_122) && !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#include <wctype.h>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_123 &' >> %t.sh
 // RUN: echo 'TEST_123=$!' >> %t.sh
 // RUN: echo "wait $TEST_107" >> %t.sh
 #if defined(TEST_123) && __cplusplus >= 201103L
-#include <experimental/forward_list>
+#include <experimental/deque>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_124 &' >> %t.sh
 // RUN: echo 'TEST_124=$!' >> %t.sh
 // RUN: echo "wait $TEST_108" >> %t.sh
 #if defined(TEST_124) && __cplusplus >= 201103L
-#include <experimental/iterator>
+#include <experimental/forward_list>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_125 &' >> %t.sh
 // RUN: echo 'TEST_125=$!' >> %t.sh
 // RUN: echo "wait $TEST_109" >> %t.sh
 #if defined(TEST_125) && __cplusplus >= 201103L
-#include <experimental/list>
+#include <experimental/iterator>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_126 &' >> %t.sh
 // RUN: echo 'TEST_126=$!' >> %t.sh
 // RUN: echo "wait $TEST_110" >> %t.sh
 #if defined(TEST_126) && __cplusplus >= 201103L
-#include <experimental/map>
+#include <experimental/list>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_127 &' >> %t.sh
 // RUN: echo 'TEST_127=$!' >> %t.sh
 // RUN: echo "wait $TEST_111" >> %t.sh
 #if defined(TEST_127) && __cplusplus >= 201103L
-#include <experimental/memory_resource>
+#include <experimental/map>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_128 &' >> %t.sh
 // RUN: echo 'TEST_128=$!' >> %t.sh
 // RUN: echo "wait $TEST_112" >> %t.sh
 #if defined(TEST_128) && __cplusplus >= 201103L
-#include <experimental/propagate_const>
+#include <experimental/memory_resource>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_129 &' >> %t.sh
 // RUN: echo 'TEST_129=$!' >> %t.sh
 // RUN: echo "wait $TEST_113" >> %t.sh
-#if defined(TEST_129) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && __cplusplus >= 201103L
-#include <experimental/regex>
+#if defined(TEST_129) && __cplusplus >= 201103L
+#include <experimental/propagate_const>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_130 &' >> %t.sh
 // RUN: echo 'TEST_130=$!' >> %t.sh
 // RUN: echo "wait $TEST_114" >> %t.sh
-#if defined(TEST_130) && __cplusplus >= 201103L
-#include <experimental/set>
+#if defined(TEST_130) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && __cplusplus >= 201103L
+#include <experimental/regex>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_131 &' >> %t.sh
 // RUN: echo 'TEST_131=$!' >> %t.sh
 // RUN: echo "wait $TEST_115" >> %t.sh
 #if defined(TEST_131) && __cplusplus >= 201103L
-#include <experimental/simd>
+#include <experimental/set>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_132 &' >> %t.sh
 // RUN: echo 'TEST_132=$!' >> %t.sh
 // RUN: echo "wait $TEST_116" >> %t.sh
 #if defined(TEST_132) && __cplusplus >= 201103L
-#include <experimental/string>
+#include <experimental/simd>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_133 &' >> %t.sh
 // RUN: echo 'TEST_133=$!' >> %t.sh
 // RUN: echo "wait $TEST_117" >> %t.sh
 #if defined(TEST_133) && __cplusplus >= 201103L
-#include <experimental/type_traits>
+#include <experimental/string>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_134 &' >> %t.sh
 // RUN: echo 'TEST_134=$!' >> %t.sh
 // RUN: echo "wait $TEST_118" >> %t.sh
 #if defined(TEST_134) && __cplusplus >= 201103L
-#include <experimental/unordered_map>
+#include <experimental/type_traits>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_135 &' >> %t.sh
 // RUN: echo 'TEST_135=$!' >> %t.sh
 // RUN: echo "wait $TEST_119" >> %t.sh
 #if defined(TEST_135) && __cplusplus >= 201103L
-#include <experimental/unordered_set>
+#include <experimental/unordered_map>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_136 &' >> %t.sh
 // RUN: echo 'TEST_136=$!' >> %t.sh
 // RUN: echo "wait $TEST_120" >> %t.sh
 #if defined(TEST_136) && __cplusplus >= 201103L
-#include <experimental/utility>
+#include <experimental/unordered_set>
 #endif
 // RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_137 &' >> %t.sh
 // RUN: echo 'TEST_137=$!' >> %t.sh
 // RUN: echo "wait $TEST_121" >> %t.sh
 #if defined(TEST_137) && __cplusplus >= 201103L
-#include <experimental/vector>
+#include <experimental/utility>
 #endif
+// RUN: echo '%{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_138 &' >> %t.sh
+// RUN: echo 'TEST_138=$!' >> %t.sh
 // RUN: echo "wait $TEST_122" >> %t.sh
+#if defined(TEST_138) && __cplusplus >= 201103L
+#include <experimental/vector>
+#endif
 // RUN: echo "wait $TEST_123" >> %t.sh
 // RUN: echo "wait $TEST_124" >> %t.sh
 // RUN: echo "wait $TEST_125" >> %t.sh
@@ -879,5 +884,6 @@
 // RUN: echo "wait $TEST_135" >> %t.sh
 // RUN: echo "wait $TEST_136" >> %t.sh
 // RUN: echo "wait $TEST_137" >> %t.sh
+// RUN: echo "wait $TEST_138" >> %t.sh
 // RUN: bash %t.sh
 // GENERATED-MARKER
diff --git a/libcxx/test/libcxx/nasty_macros.compile.pass.cpp b/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
--- a/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
+++ b/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
@@ -266,6 +266,7 @@
 #include <numbers>
 #include <numeric>
 #include <optional>
+#include <optional_formatter>
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #   include <ostream>
 #endif
diff --git a/libcxx/test/libcxx/no_assert_include.compile.pass.cpp b/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
--- a/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
+++ b/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
@@ -138,6 +138,7 @@
 #include <numbers>
 #include <numeric>
 #include <optional>
+#include <optional_formatter>
 #if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 #   include <ostream>
 #endif
diff --git a/libcxx/test/libcxx/transitive_includes.sh.cpp b/libcxx/test/libcxx/transitive_includes.sh.cpp
--- a/libcxx/test/libcxx/transitive_includes.sh.cpp
+++ b/libcxx/test/libcxx/transitive_includes.sh.cpp
@@ -345,196 +345,200 @@
 #if defined(TEST_77)
 #include <optional>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_78 > /dev/null 2> %t/header.ostream
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_78 > /dev/null 2> %t/header.optional_formatter
 #if defined(TEST_78)
-#include <ostream>
+#include <optional_formatter>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_79 > /dev/null 2> %t/header.queue
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_79 > /dev/null 2> %t/header.ostream
 #if defined(TEST_79)
-#include <queue>
+#include <ostream>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_80 > /dev/null 2> %t/header.random
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_80 > /dev/null 2> %t/header.queue
 #if defined(TEST_80)
-#include <random>
+#include <queue>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_81 > /dev/null 2> %t/header.ranges
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_81 > /dev/null 2> %t/header.random
 #if defined(TEST_81)
-#include <ranges>
+#include <random>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_82 > /dev/null 2> %t/header.ratio
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_82 > /dev/null 2> %t/header.ranges
 #if defined(TEST_82)
-#include <ratio>
+#include <ranges>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_83 > /dev/null 2> %t/header.regex
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_83 > /dev/null 2> %t/header.ratio
 #if defined(TEST_83)
-#include <regex>
+#include <ratio>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_84 > /dev/null 2> %t/header.scoped_allocator
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_84 > /dev/null 2> %t/header.regex
 #if defined(TEST_84)
-#include <scoped_allocator>
+#include <regex>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_85 > /dev/null 2> %t/header.semaphore
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_85 > /dev/null 2> %t/header.scoped_allocator
 #if defined(TEST_85)
-#include <semaphore>
+#include <scoped_allocator>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_86 > /dev/null 2> %t/header.set
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_86 > /dev/null 2> %t/header.semaphore
 #if defined(TEST_86)
+#include <semaphore>
+#endif
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_87 > /dev/null 2> %t/header.set
+#if defined(TEST_87)
 #include <set>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_88 > /dev/null 2> %t/header.shared_mutex
-#if defined(TEST_88)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_89 > /dev/null 2> %t/header.shared_mutex
+#if defined(TEST_89)
 #include <shared_mutex>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_89 > /dev/null 2> %t/header.source_location
-#if defined(TEST_89)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_90 > /dev/null 2> %t/header.source_location
+#if defined(TEST_90)
 #include <source_location>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_90 > /dev/null 2> %t/header.span
-#if defined(TEST_90)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_91 > /dev/null 2> %t/header.span
+#if defined(TEST_91)
 #include <span>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_91 > /dev/null 2> %t/header.sstream
-#if defined(TEST_91)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_92 > /dev/null 2> %t/header.sstream
+#if defined(TEST_92)
 #include <sstream>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_92 > /dev/null 2> %t/header.stack
-#if defined(TEST_92)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_93 > /dev/null 2> %t/header.stack
+#if defined(TEST_93)
 #include <stack>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_96 > /dev/null 2> %t/header.stdexcept
-#if defined(TEST_96)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_97 > /dev/null 2> %t/header.stdexcept
+#if defined(TEST_97)
 #include <stdexcept>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_100 > /dev/null 2> %t/header.streambuf
-#if defined(TEST_100)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_101 > /dev/null 2> %t/header.streambuf
+#if defined(TEST_101)
 #include <streambuf>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_101 > /dev/null 2> %t/header.string
-#if defined(TEST_101)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_102 > /dev/null 2> %t/header.string
+#if defined(TEST_102)
 #include <string>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_103 > /dev/null 2> %t/header.string_view
-#if defined(TEST_103)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_104 > /dev/null 2> %t/header.string_view
+#if defined(TEST_104)
 #include <string_view>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_104 > /dev/null 2> %t/header.strstream
-#if defined(TEST_104)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_105 > /dev/null 2> %t/header.strstream
+#if defined(TEST_105)
 #include <strstream>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_105 > /dev/null 2> %t/header.system_error
-#if defined(TEST_105)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_106 > /dev/null 2> %t/header.system_error
+#if defined(TEST_106)
 #include <system_error>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_107 > /dev/null 2> %t/header.thread
-#if defined(TEST_107)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_108 > /dev/null 2> %t/header.thread
+#if defined(TEST_108)
 #include <thread>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_108 > /dev/null 2> %t/header.tuple
-#if defined(TEST_108)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_109 > /dev/null 2> %t/header.tuple
+#if defined(TEST_109)
 #include <tuple>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_109 > /dev/null 2> %t/header.type_traits
-#if defined(TEST_109)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_110 > /dev/null 2> %t/header.type_traits
+#if defined(TEST_110)
 #include <type_traits>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_110 > /dev/null 2> %t/header.typeindex
-#if defined(TEST_110)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_111 > /dev/null 2> %t/header.typeindex
+#if defined(TEST_111)
 #include <typeindex>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_111 > /dev/null 2> %t/header.typeinfo
-#if defined(TEST_111)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_112 > /dev/null 2> %t/header.typeinfo
+#if defined(TEST_112)
 #include <typeinfo>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_113 > /dev/null 2> %t/header.unordered_map
-#if defined(TEST_113)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_114 > /dev/null 2> %t/header.unordered_map
+#if defined(TEST_114)
 #include <unordered_map>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_114 > /dev/null 2> %t/header.unordered_set
-#if defined(TEST_114)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_115 > /dev/null 2> %t/header.unordered_set
+#if defined(TEST_115)
 #include <unordered_set>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_115 > /dev/null 2> %t/header.utility
-#if defined(TEST_115)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_116 > /dev/null 2> %t/header.utility
+#if defined(TEST_116)
 #include <utility>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_116 > /dev/null 2> %t/header.valarray
-#if defined(TEST_116)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_117 > /dev/null 2> %t/header.valarray
+#if defined(TEST_117)
 #include <valarray>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_117 > /dev/null 2> %t/header.variant
-#if defined(TEST_117)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_118 > /dev/null 2> %t/header.variant
+#if defined(TEST_118)
 #include <variant>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_118 > /dev/null 2> %t/header.vector
-#if defined(TEST_118)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_119 > /dev/null 2> %t/header.vector
+#if defined(TEST_119)
 #include <vector>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_119 > /dev/null 2> %t/header.version
-#if defined(TEST_119)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_120 > /dev/null 2> %t/header.version
+#if defined(TEST_120)
 #include <version>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_122 > /dev/null 2> %t/header.experimental_deque
-#if defined(TEST_122)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_123 > /dev/null 2> %t/header.experimental_deque
+#if defined(TEST_123)
 #include <experimental/deque>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_123 > /dev/null 2> %t/header.experimental_forward_list
-#if defined(TEST_123)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_124 > /dev/null 2> %t/header.experimental_forward_list
+#if defined(TEST_124)
 #include <experimental/forward_list>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_124 > /dev/null 2> %t/header.experimental_iterator
-#if defined(TEST_124)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_125 > /dev/null 2> %t/header.experimental_iterator
+#if defined(TEST_125)
 #include <experimental/iterator>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_125 > /dev/null 2> %t/header.experimental_list
-#if defined(TEST_125)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_126 > /dev/null 2> %t/header.experimental_list
+#if defined(TEST_126)
 #include <experimental/list>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_126 > /dev/null 2> %t/header.experimental_map
-#if defined(TEST_126)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_127 > /dev/null 2> %t/header.experimental_map
+#if defined(TEST_127)
 #include <experimental/map>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_127 > /dev/null 2> %t/header.experimental_memory_resource
-#if defined(TEST_127)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_128 > /dev/null 2> %t/header.experimental_memory_resource
+#if defined(TEST_128)
 #include <experimental/memory_resource>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_128 > /dev/null 2> %t/header.experimental_propagate_const
-#if defined(TEST_128)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_129 > /dev/null 2> %t/header.experimental_propagate_const
+#if defined(TEST_129)
 #include <experimental/propagate_const>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_129 > /dev/null 2> %t/header.experimental_regex
-#if defined(TEST_129)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_130 > /dev/null 2> %t/header.experimental_regex
+#if defined(TEST_130)
 #include <experimental/regex>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_130 > /dev/null 2> %t/header.experimental_set
-#if defined(TEST_130)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_131 > /dev/null 2> %t/header.experimental_set
+#if defined(TEST_131)
 #include <experimental/set>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_131 > /dev/null 2> %t/header.experimental_simd
-#if defined(TEST_131)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_132 > /dev/null 2> %t/header.experimental_simd
+#if defined(TEST_132)
 #include <experimental/simd>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_132 > /dev/null 2> %t/header.experimental_string
-#if defined(TEST_132)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_133 > /dev/null 2> %t/header.experimental_string
+#if defined(TEST_133)
 #include <experimental/string>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_133 > /dev/null 2> %t/header.experimental_type_traits
-#if defined(TEST_133)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_134 > /dev/null 2> %t/header.experimental_type_traits
+#if defined(TEST_134)
 #include <experimental/type_traits>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_134 > /dev/null 2> %t/header.experimental_unordered_map
-#if defined(TEST_134)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_135 > /dev/null 2> %t/header.experimental_unordered_map
+#if defined(TEST_135)
 #include <experimental/unordered_map>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_135 > /dev/null 2> %t/header.experimental_unordered_set
-#if defined(TEST_135)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_136 > /dev/null 2> %t/header.experimental_unordered_set
+#if defined(TEST_136)
 #include <experimental/unordered_set>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_136 > /dev/null 2> %t/header.experimental_utility
-#if defined(TEST_136)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_137 > /dev/null 2> %t/header.experimental_utility
+#if defined(TEST_137)
 #include <experimental/utility>
 #endif
-// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_137 > /dev/null 2> %t/header.experimental_vector
-#if defined(TEST_137)
+// RUN: %{cxx} %s %{flags} %{compile_flags} --trace-includes -fshow-skipped-includes --preprocess -DTEST_138 > /dev/null 2> %t/header.experimental_vector
+#if defined(TEST_138)
 #include <experimental/vector>
 #endif
 // RUN: %{python} %S/transitive_includes_to_csv.py %t > %t/transitive_includes.csv
diff --git a/libcxx/test/libcxx/transitive_includes/cxx03.csv b/libcxx/test/libcxx/transitive_includes/cxx03.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx03.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx03.csv
@@ -597,6 +597,19 @@
 optional utility
 optional variant
 optional version
+optional_formatter array
+optional_formatter cerrno
+optional_formatter concepts
+optional_formatter cstddef
+optional_formatter cstdint
+optional_formatter cstdlib
+optional_formatter limits
+optional_formatter locale
+optional_formatter optional
+optional_formatter stdexcept
+optional_formatter string
+optional_formatter string_view
+optional_formatter tuple
 ostream atomic
 ostream bitset
 ostream cerrno
diff --git a/libcxx/test/libcxx/transitive_includes/cxx11.csv b/libcxx/test/libcxx/transitive_includes/cxx11.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx11.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx11.csv
@@ -598,6 +598,19 @@
 optional utility
 optional variant
 optional version
+optional_formatter array
+optional_formatter cerrno
+optional_formatter concepts
+optional_formatter cstddef
+optional_formatter cstdint
+optional_formatter cstdlib
+optional_formatter limits
+optional_formatter locale
+optional_formatter optional
+optional_formatter stdexcept
+optional_formatter string
+optional_formatter string_view
+optional_formatter tuple
 ostream atomic
 ostream bitset
 ostream cerrno
diff --git a/libcxx/test/libcxx/transitive_includes/cxx14.csv b/libcxx/test/libcxx/transitive_includes/cxx14.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx14.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx14.csv
@@ -600,6 +600,19 @@
 optional utility
 optional variant
 optional version
+optional_formatter array
+optional_formatter cerrno
+optional_formatter concepts
+optional_formatter cstddef
+optional_formatter cstdint
+optional_formatter cstdlib
+optional_formatter limits
+optional_formatter locale
+optional_formatter optional
+optional_formatter stdexcept
+optional_formatter string
+optional_formatter string_view
+optional_formatter tuple
 ostream atomic
 ostream bitset
 ostream cerrno
diff --git a/libcxx/test/libcxx/transitive_includes/cxx17.csv b/libcxx/test/libcxx/transitive_includes/cxx17.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx17.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx17.csv
@@ -600,6 +600,19 @@
 optional utility
 optional variant
 optional version
+optional_formatter array
+optional_formatter cerrno
+optional_formatter concepts
+optional_formatter cstddef
+optional_formatter cstdint
+optional_formatter cstdlib
+optional_formatter limits
+optional_formatter locale
+optional_formatter optional
+optional_formatter stdexcept
+optional_formatter string
+optional_formatter string_view
+optional_formatter tuple
 ostream atomic
 ostream bitset
 ostream cerrno
diff --git a/libcxx/test/libcxx/transitive_includes/cxx20.csv b/libcxx/test/libcxx/transitive_includes/cxx20.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx20.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx20.csv
@@ -606,6 +606,19 @@
 optional utility
 optional variant
 optional version
+optional_formatter array
+optional_formatter cerrno
+optional_formatter concepts
+optional_formatter cstddef
+optional_formatter cstdint
+optional_formatter cstdlib
+optional_formatter limits
+optional_formatter locale
+optional_formatter optional
+optional_formatter stdexcept
+optional_formatter string
+optional_formatter string_view
+optional_formatter tuple
 ostream atomic
 ostream bitset
 ostream cerrno
diff --git a/libcxx/test/libcxx/transitive_includes/cxx2b.csv b/libcxx/test/libcxx/transitive_includes/cxx2b.csv
--- a/libcxx/test/libcxx/transitive_includes/cxx2b.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx2b.csv
@@ -401,6 +401,21 @@
 optional new
 optional stdexcept
 optional version
+optional_formatter array
+optional_formatter cerrno
+optional_formatter concepts
+optional_formatter cstddef
+optional_formatter cstdint
+optional_formatter cstdlib
+optional_formatter initializer_list
+optional_formatter limits
+optional_formatter locale
+optional_formatter new
+optional_formatter optional
+optional_formatter stdexcept
+optional_formatter string
+optional_formatter string_view
+optional_formatter tuple
 ostream bitset
 ostream cerrno
 ostream cstddef
diff --git a/libcxx/test/std/utilities/format/format.formattable/concept.formattable.compile.pass.cpp b/libcxx/test/std/utilities/format/format.formattable/concept.formattable.compile.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formattable/concept.formattable.compile.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formattable/concept.formattable.compile.pass.cpp
@@ -29,6 +29,7 @@
 #include <memory>
 #include <map>
 #include <optional>
+#include <optional_formatter>
 #include <queue>
 #include <set>
 #include <stack>
@@ -299,7 +300,7 @@
   assert_is_not_formattable<void (c::*)(), CharT>();
   assert_is_not_formattable<void (c::*)() const, CharT>();
 
-  assert_is_not_formattable<std::optional<int>, CharT>();
+  assert_is_formattable<std::optional<int>, CharT>();
   assert_is_not_formattable<std::variant<int>, CharT>();
 
   assert_is_not_formattable<std::shared_ptr<c>, CharT>();
diff --git a/libcxx/test/std/utilities/format/format.functions/optional_formatter.pass.cpp b/libcxx/test/std/utilities/format/format.functions/optional_formatter.pass.cpp
new file mode 100644
--- /dev/null
+++ b/libcxx/test/std/utilities/format/format.functions/optional_formatter.pass.cpp
@@ -0,0 +1,29 @@
+//===----------------------------------------------------------------------===//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-has-no-incomplete-format
+
+// XFAIL: availability-fp_to_chars-missing
+
+#include <cassert>
+#include <format>
+#include <iostream>
+#include <map>
+#include <optional_formatter>
+#include <set>
+#include <vector>
+
+int main(int, char**) {
+  assert(std::format("{}", std::optional<int>{1}) == "[1]");
+  assert(std::format("{}", std::optional<std::vector<int>>{{1, 2, 3}}) == "[[1, 2, 3]]");
+  assert(std::format("{}", std::optional<std::tuple<int>>{{1}}) == "[(1)]");
+  assert(std::format("{}", std::optional<std::set<int>>{{1}}) == "[{1}]");
+  assert(std::format("{}", std::optional<std::map<int, int>>{{{1, 1}}}) == "[{1: 1}]");
+
+  return 0;
+}