diff --git a/libcxx/include/__chrono/formatter.h b/libcxx/include/__chrono/formatter.h
--- a/libcxx/include/__chrono/formatter.h
+++ b/libcxx/include/__chrono/formatter.h
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___CHRONO_FORMATTER_H
 #define _LIBCPP___CHRONO_FORMATTER_H
 
+#include <__availability>
 #include <__chrono/convert_to_tm.h>
 #include <__chrono/day.h>
 #include <__chrono/duration.h>
@@ -44,7 +45,12 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
+// On Apple back-deployment targets the format functions are not available with
+// and #ifndef. This will cause compilation failures when using these
+// functions. Therefore make these functions unavailable when used on these
+// platforms.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) &&                                              \
+    !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __formatter {
 
@@ -367,7 +373,8 @@
 };
 
 template <class _Rep, class _Period, __fmt_char_type _CharT>
-struct formatter<chrono::duration<_Rep, _Period>, _CharT> : public __formatter_chrono<_CharT> {
+struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<chrono::duration<_Rep, _Period>, _CharT>
+    : public __formatter_chrono<_CharT> {
 public:
   using _Base = __formatter_chrono<_CharT>;
 
@@ -436,7 +443,7 @@
   }
 };
 
-#endif // if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__chrono/ostream.h b/libcxx/include/__chrono/ostream.h
--- a/libcxx/include/__chrono/ostream.h
+++ b/libcxx/include/__chrono/ostream.h
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___CHRONO_OSTREAM_H
 #define _LIBCPP___CHRONO_OSTREAM_H
 
+#include <__availability>
 #include <__chrono/day.h>
 #include <__chrono/duration.h>
 #include <__chrono/month.h>
@@ -28,7 +29,12 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
+// On Apple back-deployment targets the format functions are not available with
+// and #ifndef. This will cause compilation failures when using these
+// functions. Therefore make these functions unavailable when used on these
+// platforms.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) &&                                              \
+    !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace chrono {
 
@@ -138,7 +144,7 @@
 
 } // namespace chrono
 
-#endif //if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
+#endif //if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__chrono/parser_std_format_spec.h b/libcxx/include/__chrono/parser_std_format_spec.h
--- a/libcxx/include/__chrono/parser_std_format_spec.h
+++ b/libcxx/include/__chrono/parser_std_format_spec.h
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___CHRONO_PARSER_STD_FORMAT_SPEC_H
 #define _LIBCPP___CHRONO_PARSER_STD_FORMAT_SPEC_H
 
+#include <__availability>
 #include <__config>
 #include <__format/concepts.h>
 #include <__format/format_error.h>
@@ -24,7 +25,12 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) &&                                              \
+    !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __format_spec {
 
@@ -396,7 +402,7 @@
 
 } // namespace __format_spec
 
-#endif //_LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/concepts.h b/libcxx/include/__format/concepts.h
--- a/libcxx/include/__format/concepts.h
+++ b/libcxx/include/__format/concepts.h
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___FORMAT_CONCEPTS_H
 #define _LIBCPP___FORMAT_CONCEPTS_H
 
+#include <__availability>
 #include <__concepts/same_as.h>
 #include <__concepts/semiregular.h>
 #include <__config>
@@ -34,6 +35,15 @@
 #  endif
     ;
 
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+//
+// Note the concept above is used in other places and doesn't suffer from the
+// CTAD issue.
+#  if !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
+
 // The output iterator isn't specified. A formatter should accept any
 // output_iterator. This iterator is a minimal iterator to test the concept.
 // (Note testing for (w)format_context would be a valid choice, but requires
@@ -57,7 +67,9 @@
 template <class _Tp, class _CharT>
 concept formattable = __formattable<_Tp, _CharT>;
 #  endif //_LIBCPP_STD_VER > 20
-#endif //_LIBCPP_STD_VER > 17
+#  endif // !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
+
+#endif   // _LIBCPP_STD_VER > 17
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/format_arg.h b/libcxx/include/__format/format_arg.h
--- a/libcxx/include/__format/format_arg.h
+++ b/libcxx/include/__format/format_arg.h
@@ -11,6 +11,7 @@
 #define _LIBCPP___FORMAT_FORMAT_ARG_H
 
 #include <__assert>
+#include <__availability>
 #include <__concepts/arithmetic.h>
 #include <__config>
 #include <__format/format_error.h>
@@ -30,7 +31,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __format {
 /// The type stored in @ref basic_format_arg.
@@ -94,8 +99,7 @@
 // This function is not user obervable, so it can directly use the non-standard
 // types of the "variant". See __arg_t for more details.
 template <class _Visitor, class _Context>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT decltype(auto)
-__visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
+_LIBCPP_HIDE_FROM_ABI decltype(auto) __visit_format_arg(_Visitor&& __vis, basic_format_arg<_Context> __arg) {
   switch (__arg.__type_) {
   case __format::__arg_t::__none:
     return _VSTD::invoke(_VSTD::forward<_Visitor>(__vis), __arg.__value_.__monostate_);
@@ -259,7 +263,7 @@
 };
 
 template <class _Context>
-class _LIBCPP_TEMPLATE_VIS basic_format_arg<_Context>::handle {
+class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT basic_format_arg<_Context>::handle {
 public:
   _LIBCPP_HIDE_FROM_ABI
   void format(basic_format_parse_context<char_type>& __parse_ctx, _Context& __ctx) const {
@@ -295,7 +299,7 @@
   }
 }
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/format_arg_store.h b/libcxx/include/__format/format_arg_store.h
--- a/libcxx/include/__format/format_arg_store.h
+++ b/libcxx/include/__format/format_arg_store.h
@@ -14,6 +14,7 @@
 #  pragma GCC system_header
 #endif
 
+#include <__availability>
 #include <__concepts/arithmetic.h>
 #include <__concepts/same_as.h>
 #include <__config>
@@ -27,7 +28,10 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This header is disabled due to CTAD failures
+// in included headers.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __format {
 
@@ -247,7 +251,7 @@
   _Storage __storage;
 };
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/format_args.h b/libcxx/include/__format/format_args.h
--- a/libcxx/include/__format/format_args.h
+++ b/libcxx/include/__format/format_args.h
@@ -24,7 +24,10 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This header is disabled due to CTAD failures
+// in included headers.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 template <class _Context>
 class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT basic_format_args {
@@ -73,7 +76,7 @@
 };
 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_format_args);
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/format_context.h b/libcxx/include/__format/format_context.h
--- a/libcxx/include/__format/format_context.h
+++ b/libcxx/include/__format/format_context.h
@@ -31,7 +31,10 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This header is disabled due to CTAD failures
+// in included headers.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 template <class _OutIt, class _CharT>
 requires output_iterator<_OutIt, const _CharT&>
@@ -62,12 +65,11 @@
 #endif
 
 using format_context =
-    basic_format_context<back_insert_iterator<__format::__output_buffer<char>>,
-                         char>;
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-using wformat_context = basic_format_context<
-    back_insert_iterator<__format::__output_buffer<wchar_t>>, wchar_t>;
-#endif
+    _LIBCPP_AVAILABILITY_FORMAT basic_format_context<back_insert_iterator<__format::__output_buffer<char>>, char>;
+#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+using wformat_context = _LIBCPP_AVAILABILITY_FORMAT
+    basic_format_context< back_insert_iterator<__format::__output_buffer<wchar_t>>, wchar_t>;
+#  endif
 
 template <class _OutIt, class _CharT>
 requires output_iterator<_OutIt, const _CharT&>
@@ -140,7 +142,7 @@
 };
 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_format_context);
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/format_functions.h b/libcxx/include/__format/format_functions.h
--- a/libcxx/include/__format/format_functions.h
+++ b/libcxx/include/__format/format_functions.h
@@ -10,47 +10,49 @@
 #ifndef _LIBCPP___FORMAT_FORMAT_FUNCTIONS
 #define _LIBCPP___FORMAT_FORMAT_FUNCTIONS
 
-// TODO FMT This is added to fix Apple back-deployment.
-#include <version>
-#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
-
-#include <__algorithm/clamp.h>
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
 #include <__availability>
-#include <__concepts/convertible_to.h>
-#include <__concepts/same_as.h>
 #include <__config>
-#include <__debug>
-#include <__format/buffer.h>
-#include <__format/format_arg.h>
-#include <__format/format_arg_store.h>
-#include <__format/format_args.h>
-#include <__format/format_context.h>
-#include <__format/format_error.h>
-#include <__format/format_parse_context.h>
-#include <__format/format_string.h>
-#include <__format/format_to_n_result.h>
-#include <__format/formatter.h>
-#include <__format/formatter_bool.h>
-#include <__format/formatter_char.h>
-#include <__format/formatter_floating_point.h>
-#include <__format/formatter_integer.h>
-#include <__format/formatter_pointer.h>
-#include <__format/formatter_string.h>
-#include <__format/parser_std_format_spec.h>
-#include <__iterator/back_insert_iterator.h>
-#include <__iterator/incrementable_traits.h>
-#include <__variant/monostate.h>
-#include <array>
-#include <string>
-#include <string_view>
-
-#ifndef _LIBCPP_HAS_NO_LOCALIZATION
-#include <locale>
-#endif
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
+
+#  include <__algorithm/clamp.h>
+#  include <__concepts/convertible_to.h>
+#  include <__concepts/same_as.h>
+#  include <__debug>
+#  include <__format/buffer.h>
+#  include <__format/format_arg.h>
+#  include <__format/format_arg_store.h>
+#  include <__format/format_args.h>
+#  include <__format/format_context.h>
+#  include <__format/format_error.h>
+#  include <__format/format_parse_context.h>
+#  include <__format/format_string.h>
+#  include <__format/format_to_n_result.h>
+#  include <__format/formatter.h>
+#  include <__format/formatter_bool.h>
+#  include <__format/formatter_char.h>
+#  include <__format/formatter_floating_point.h>
+#  include <__format/formatter_integer.h>
+#  include <__format/formatter_pointer.h>
+#  include <__format/formatter_string.h>
+#  include <__format/parser_std_format_spec.h>
+#  include <__iterator/back_insert_iterator.h>
+#  include <__iterator/incrementable_traits.h>
+#  include <__variant/monostate.h>
+#  include <array>
+#  include <string>
+#  include <string_view>
+
+#  ifndef _LIBCPP_HAS_NO_LOCALIZATION
+#    include <locale>
+#  endif
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -61,10 +63,10 @@
 // under heavy development and not all classes are stable it makes no sense
 // to do this optimization now.
 
-using format_args = basic_format_args<format_context>;
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-using wformat_args = basic_format_args<wformat_context>;
-#endif
+using format_args = _LIBCPP_AVAILABILITY_FORMAT basic_format_args<format_context>;
+#    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+using wformat_args = _LIBCPP_AVAILABILITY_FORMAT basic_format_args<wformat_context>;
+#    endif
 
 template <class _Context = format_context, class... _Args>
 _LIBCPP_HIDE_FROM_ABI __format_arg_store<_Context, _Args...> make_format_args(_Args&&... __args) {
@@ -333,7 +335,7 @@
 } // namespace __format
 
 template <class _CharT, class... _Args>
-struct _LIBCPP_TEMPLATE_VIS basic_format_string {
+struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT basic_format_string {
   template <class _Tp>
     requires convertible_to<const _Tp&, basic_string_view<_CharT>>
   consteval basic_format_string(const _Tp& __str) : __str_{__str} {
@@ -341,9 +343,7 @@
                            _Context{__types_.data(), __handles_.data(), sizeof...(_Args)});
   }
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT constexpr basic_string_view<_CharT> get() const noexcept {
-    return __str_;
-  }
+  _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<_CharT> get() const noexcept { return __str_; }
 
 private:
   basic_string_view<_CharT> __str_;
@@ -379,18 +379,19 @@
 };
 
 template <class... _Args>
-using format_string = basic_format_string<char, type_identity_t<_Args>...>;
+using format_string = _LIBCPP_AVAILABILITY_FORMAT basic_format_string<char, type_identity_t<_Args>...>;
 
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 template <class... _Args>
-using wformat_string = basic_format_string<wchar_t, type_identity_t<_Args>...>;
-#endif
+using wformat_string = _LIBCPP_AVAILABILITY_FORMAT basic_format_string<wchar_t, type_identity_t<_Args>...>;
+#    endif
 
 template <class _OutIt, class _CharT, class _FormatOutIt>
-requires(output_iterator<_OutIt, const _CharT&>) _LIBCPP_HIDE_FROM_ABI _OutIt
-    __vformat_to(
-        _OutIt __out_it, basic_string_view<_CharT> __fmt,
-        basic_format_args<basic_format_context<_FormatOutIt, _CharT>> __args) {
+  requires(output_iterator<_OutIt, const _CharT&>)
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_FORMAT _OutIt __vformat_to(
+    _OutIt __out_it,
+    basic_string_view<_CharT> __fmt,
+    basic_format_args<basic_format_context<_FormatOutIt, _CharT>> __args) {
   if constexpr (same_as<_OutIt, _FormatOutIt>)
     return _VSTD::__format::__vformat_to(basic_format_parse_context{__fmt, __args.__size()},
                                          _VSTD::__format_context_create(_VSTD::move(__out_it), __args));
@@ -658,6 +659,6 @@
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
+#endif // !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 #endif // _LIBCPP___FORMAT_FORMAT_FUNCTIONS
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
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___FORMAT_FORMAT_PARSE_CONTEXT_H
 #define _LIBCPP___FORMAT_FORMAT_PARSE_CONTEXT_H
 
+#include <__availability>
 #include <__config>
 #include <__format/format_error.h>
 #include <string_view>
@@ -20,7 +21,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 template <class _CharT>
 class _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT basic_format_parse_context {
@@ -90,12 +95,12 @@
 };
 _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(basic_format_parse_context);
 
-using format_parse_context = basic_format_parse_context<char>;
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-using wformat_parse_context = basic_format_parse_context<wchar_t>;
-#endif
+using format_parse_context = _LIBCPP_AVAILABILITY_FORMAT basic_format_parse_context<char>;
+#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+using wformat_parse_context = _LIBCPP_AVAILABILITY_FORMAT basic_format_parse_context<wchar_t>;
+#  endif
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_bool.h b/libcxx/include/__format/formatter_bool.h
--- a/libcxx/include/__format/formatter_bool.h
+++ b/libcxx/include/__format/formatter_bool.h
@@ -33,7 +33,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 template <__fmt_char_type _CharT>
 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<bool, _CharT> {
@@ -71,7 +75,7 @@
   __format_spec::__parser<_CharT> __parser_;
 };
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_char.h b/libcxx/include/__format/formatter_char.h
--- a/libcxx/include/__format/formatter_char.h
+++ b/libcxx/include/__format/formatter_char.h
@@ -28,10 +28,14 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 template <__fmt_char_type _CharT>
-struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT __formatter_char {
+struct _LIBCPP_TEMPLATE_VIS __formatter_char {
 public:
   _LIBCPP_HIDE_FROM_ABI constexpr auto
   parse(basic_format_parse_context<_CharT>& __parse_ctx) -> decltype(__parse_ctx.begin()) {
@@ -86,7 +90,7 @@
 
 #  endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
-#endif //_LIBCPP_STD_VER > 17
+#endif   // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_floating_point.h b/libcxx/include/__format/formatter_floating_point.h
--- a/libcxx/include/__format/formatter_floating_point.h
+++ b/libcxx/include/__format/formatter_floating_point.h
@@ -43,7 +43,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __formatter {
 
@@ -748,7 +752,7 @@
 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<long double, _CharT>
     : public __formatter_floating_point<_CharT> {};
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_integer.h b/libcxx/include/__format/formatter_integer.h
--- a/libcxx/include/__format/formatter_integer.h
+++ b/libcxx/include/__format/formatter_integer.h
@@ -26,13 +26,16 @@
 #  pragma GCC system_header
 #endif
 
-    _LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
-
-    template <__fmt_char_type _CharT>
-    struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT __formatter_integer {
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
+template <__fmt_char_type _CharT>
+struct _LIBCPP_TEMPLATE_VIS __formatter_integer {
 public:
   _LIBCPP_HIDE_FROM_ABI constexpr auto
   parse(basic_format_parse_context<_CharT>& __parse_ctx) -> decltype(__parse_ctx.begin()) {
@@ -100,7 +103,7 @@
     : public __formatter_integer<_CharT> {};
 #  endif
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_integral.h b/libcxx/include/__format/formatter_integral.h
--- a/libcxx/include/__format/formatter_integral.h
+++ b/libcxx/include/__format/formatter_integral.h
@@ -10,6 +10,7 @@
 #ifndef _LIBCPP___FORMAT_FORMATTER_INTEGRAL_H
 #define _LIBCPP___FORMAT_FORMATTER_INTEGRAL_H
 
+#include <__availability>
 #include <__concepts/arithmetic.h>
 #include <__concepts/same_as.h>
 #include <__config>
@@ -36,7 +37,10 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This header is disabled due to CTAD failures
+// in included headers.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __formatter {
 
@@ -354,7 +358,7 @@
 
 } // namespace __formatter
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_output.h b/libcxx/include/__format/formatter_output.h
--- a/libcxx/include/__format/formatter_output.h
+++ b/libcxx/include/__format/formatter_output.h
@@ -13,6 +13,7 @@
 #include <__algorithm/ranges_copy.h>
 #include <__algorithm/ranges_fill_n.h>
 #include <__algorithm/ranges_transform.h>
+#include <__availability>
 #include <__chrono/statically_widen.h>
 #include <__concepts/same_as.h>
 #include <__config>
@@ -37,7 +38,10 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This header is disabled due to CTAD failures
+// in included headers.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __formatter {
 
@@ -552,7 +556,7 @@
 
 } // namespace __formatter
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_pointer.h b/libcxx/include/__format/formatter_pointer.h
--- a/libcxx/include/__format/formatter_pointer.h
+++ b/libcxx/include/__format/formatter_pointer.h
@@ -27,7 +27,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 template <__fmt_char_type _CharT>
 struct _LIBCPP_TEMPLATE_VIS __formatter_pointer {
@@ -66,7 +70,7 @@
 struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<const void*, _CharT>
     : public __formatter_pointer<_CharT> {};
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/formatter_string.h b/libcxx/include/__format/formatter_string.h
--- a/libcxx/include/__format/formatter_string.h
+++ b/libcxx/include/__format/formatter_string.h
@@ -27,7 +27,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 template <__fmt_char_type _CharT>
 struct _LIBCPP_TEMPLATE_VIS __formatter_string {
@@ -147,7 +151,7 @@
   }
 };
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/__format/parser_std_format_spec.h b/libcxx/include/__format/parser_std_format_spec.h
--- a/libcxx/include/__format/parser_std_format_spec.h
+++ b/libcxx/include/__format/parser_std_format_spec.h
@@ -42,7 +42,11 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER > 17
+// When format is not available on Apple back-deployment targets the
+// compilation will fail. This is caused by instantiating templates where CTAD
+// is used. (This might be a compiler bug.) To avoid instantiations make this
+// header a NOP when used on back-deployment targets.
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 namespace __format_spec {
 
@@ -918,7 +922,7 @@
 
 } // namespace __format_spec
 
-#endif //_LIBCPP_STD_VER > 17
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_AVAILABILITY_DISABLE_FTM___cpp_lib_format)
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/chrono b/libcxx/include/chrono
--- a/libcxx/include/chrono
+++ b/libcxx/include/chrono
@@ -721,7 +721,7 @@
 #  include <__chrono/ostream.h>
 #  include <__chrono/parser_std_format_spec.h>
 #  include <__chrono/statically_widen.h>
-#endif
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT) && _LIBCPP_STD_VER > 17
 
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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
@@ -27,6 +27,11 @@
 // This test uses --trace-includes, which is not supported by GCC.
 // UNSUPPORTED: gcc
 
+// This test doesn't work properly on back-deployment targets. This is caused
+// by the availibility of the format headers. They are partly disabled due to
+// CTAD issues.
+// UNSUPPORTED: use_system_cxx_lib && target={{.+}}-apple-macosx{{.+}}
+
 // This test doesn't work on AIX, but it should. Needs investigation.
 // XFAIL: buildhost=aix
 
diff --git a/libcxx/test/libcxx/utilities/format/format.arguments/format.arg/arg_t.compile.pass.cpp b/libcxx/test/libcxx/utilities/format/format.arguments/format.arg/arg_t.compile.pass.cpp
--- a/libcxx/test/libcxx/utilities/format/format.arguments/format.arg/arg_t.compile.pass.cpp
+++ b/libcxx/test/libcxx/utilities/format/format.arguments/format.arg/arg_t.compile.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // namespace __format { enum class __arg_t : uint8_t{...}; }
diff --git a/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp b/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp
--- a/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp
+++ b/libcxx/test/libcxx/utilities/format/format.formatter/format.context/types.compile.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // Class typedefs:
diff --git a/libcxx/test/std/time/time.cal/time.cal.day/time.cal.day.nonmembers/ostream.pass.cpp b/libcxx/test/std/time/time.cal/time.cal.day/time.cal.day.nonmembers/ostream.pass.cpp
--- a/libcxx/test/std/time/time.cal/time.cal.day/time.cal.day.nonmembers/ostream.pass.cpp
+++ b/libcxx/test/std/time/time.cal/time.cal.day/time.cal.day.nonmembers/ostream.pass.cpp
@@ -16,6 +16,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 // class day;
 
diff --git a/libcxx/test/std/time/time.cal/time.cal.month/time.cal.month.nonmembers/ostream.pass.cpp b/libcxx/test/std/time/time.cal/time.cal.month/time.cal.month.nonmembers/ostream.pass.cpp
--- a/libcxx/test/std/time/time.cal/time.cal.month/time.cal.month.nonmembers/ostream.pass.cpp
+++ b/libcxx/test/std/time/time.cal/time.cal.month/time.cal.month.nonmembers/ostream.pass.cpp
@@ -16,6 +16,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 
 // class month;
diff --git a/libcxx/test/std/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/ostream.pass.cpp b/libcxx/test/std/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/ostream.pass.cpp
--- a/libcxx/test/std/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/ostream.pass.cpp
+++ b/libcxx/test/std/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/ostream.pass.cpp
@@ -13,6 +13,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 // class weekday;
 
diff --git a/libcxx/test/std/time/time.cal/time.cal.year/time.cal.year.nonmembers/ostream.pass.cpp b/libcxx/test/std/time/time.cal/time.cal.year/time.cal.year.nonmembers/ostream.pass.cpp
--- a/libcxx/test/std/time/time.cal/time.cal.year/time.cal.year.nonmembers/ostream.pass.cpp
+++ b/libcxx/test/std/time/time.cal/time.cal.year/time.cal.year.nonmembers/ostream.pass.cpp
@@ -16,6 +16,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 // class year;
 
diff --git a/libcxx/test/std/time/time.duration/time.duration.nonmember/ostream.pass.cpp b/libcxx/test/std/time/time.duration/time.duration.nonmember/ostream.pass.cpp
--- a/libcxx/test/std/time/time.duration/time.duration.nonmember/ostream.pass.cpp
+++ b/libcxx/test/std/time/time.duration/time.duration.nonmember/ostream.pass.cpp
@@ -16,6 +16,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 
 // template<class Rep, class Period = ratio<1>> class duration;
diff --git a/libcxx/test/std/time/time.syn/formatter.day.pass.cpp b/libcxx/test/std/time/time.syn/formatter.day.pass.cpp
--- a/libcxx/test/std/time/time.syn/formatter.day.pass.cpp
+++ b/libcxx/test/std/time/time.syn/formatter.day.pass.cpp
@@ -15,6 +15,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 
 // template<class charT> struct formatter<chrono::day, charT>;
diff --git a/libcxx/test/std/time/time.syn/formatter.duration.pass.cpp b/libcxx/test/std/time/time.syn/formatter.duration.pass.cpp
--- a/libcxx/test/std/time/time.syn/formatter.duration.pass.cpp
+++ b/libcxx/test/std/time/time.syn/formatter.duration.pass.cpp
@@ -15,6 +15,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 
 //  template<class Rep, class Period, class charT>
diff --git a/libcxx/test/std/time/time.syn/formatter.month.pass.cpp b/libcxx/test/std/time/time.syn/formatter.month.pass.cpp
--- a/libcxx/test/std/time/time.syn/formatter.month.pass.cpp
+++ b/libcxx/test/std/time/time.syn/formatter.month.pass.cpp
@@ -12,6 +12,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 
 // template<class charT> struct formatter<chrono::month, charT>;
diff --git a/libcxx/test/std/time/time.syn/formatter.weekday.pass.cpp b/libcxx/test/std/time/time.syn/formatter.weekday.pass.cpp
--- a/libcxx/test/std/time/time.syn/formatter.weekday.pass.cpp
+++ b/libcxx/test/std/time/time.syn/formatter.weekday.pass.cpp
@@ -15,6 +15,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 
 // template<class charT> struct formatter<chrono::weekday, charT>;
diff --git a/libcxx/test/std/time/time.syn/formatter.year.pass.cpp b/libcxx/test/std/time/time.syn/formatter.year.pass.cpp
--- a/libcxx/test/std/time/time.syn/formatter.year.pass.cpp
+++ b/libcxx/test/std/time/time.syn/formatter.year.pass.cpp
@@ -15,6 +15,9 @@
 // REQUIRES: locale.fr_FR.UTF-8
 // REQUIRES: locale.ja_JP.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <chrono>
 
 // template<class charT> struct formatter<chrono::year, charT>;
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class Context = format_context, class... Args>
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_format_args.sh.cpp
@@ -9,6 +9,9 @@
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 // UNSUPPORTED: no-wide-characters
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Validate it works regardless of the signedness of `char`.
 // RUN: %{cxx} %{flags} %{compile_flags} -fsigned-char -fsyntax-only %s
 // RUN: %{cxx} %{flags} %{compile_flags} -funsigned-char -fsyntax-only %s
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_wformat_args.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_wformat_args.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_wformat_args.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg.store/make_wformat_args.pass.cpp
@@ -9,6 +9,9 @@
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 // XFAIL: no-wide-characters
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class... Args>
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/ctor.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/ctor.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/ctor.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // basic_format_arg() noexcept;
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/operator_bool.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/operator_bool.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/operator_bool.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/operator_bool.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // explicit operator bool() const noexcept
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.arg/visit_format_arg.pass.cpp
@@ -9,7 +9,7 @@
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
 // This test requires the dylib support introduced in D92214.
-// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14|15}}
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
 
 // <format>
 
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.args/ctor.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.args/ctor.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.args/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.args/ctor.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // basic_format_args() noexcept;
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.args/get.pass.cpp
@@ -9,7 +9,7 @@
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
 // This test requires the dylib support introduced in D92214.
-// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14|15}}
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
 
 // <format>
 
diff --git a/libcxx/test/std/utilities/format/format.arguments/format.args/types.compile.pass.cpp b/libcxx/test/std/utilities/format/format.arguments/format.args/types.compile.pass.cpp
--- a/libcxx/test/std/utilities/format/format.arguments/format.args/types.compile.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.arguments/format.args/types.compile.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // Namespace std typedefs:
diff --git a/libcxx/test/std/utilities/format/format.fmt.string/ctor.verify.cpp b/libcxx/test/std/utilities/format/format.fmt.string/ctor.verify.cpp
--- a/libcxx/test/std/utilities/format/format.fmt.string/ctor.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.fmt.string/ctor.verify.cpp
@@ -12,6 +12,9 @@
 // libc++ supports basic_format_string in C++20 as an extension
 // UNSUPPORTED: !stdlib=libc++ && c++20
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class charT, class... Args>
diff --git a/libcxx/test/std/utilities/format/format.fmt.string/get.pass.cpp b/libcxx/test/std/utilities/format/format.fmt.string/get.pass.cpp
--- a/libcxx/test/std/utilities/format/format.fmt.string/get.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.fmt.string/get.pass.cpp
@@ -12,6 +12,9 @@
 // libc++ supports basic_format_string in C++20 as an extension
 // UNSUPPORTED: !stdlib=libc++ && c++20
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class charT, class... Args>
diff --git a/libcxx/test/std/utilities/format/format.fmt.string/types.compile.pass.cpp b/libcxx/test/std/utilities/format/format.fmt.string/types.compile.pass.cpp
--- a/libcxx/test/std/utilities/format/format.fmt.string/types.compile.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.fmt.string/types.compile.pass.cpp
@@ -12,6 +12,9 @@
 // libc++ supports basic_format_string in C++20 as an extension
 // UNSUPPORTED: !stdlib=libc++ && c++20
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 //  template<class... Args>
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
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class T, class charT>
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/advance_to.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/advance_to.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/advance_to.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/advance_to.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // void advance_to(iterator it);
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/arg.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // basic_format_arg<basic_format_context> arg(size_t id) const;
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/ctor.pass.cpp
@@ -12,6 +12,9 @@
 // REQUIRES: locale.en_US.UTF-8
 // REQUIRES: locale.fr_FR.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // The Standard does not specifiy a constructor
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/locale.pass.cpp
@@ -12,6 +12,9 @@
 // REQUIRES: locale.en_US.UTF-8
 // REQUIRES: locale.fr_FR.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // std::locale locale();
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/out.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/out.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/out.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.context/format.context/out.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // iterator out();
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.handle.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // A user defined formatter using
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.bool.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // [format.formatter.spec]:
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.c_string.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // C++23 the formatter is a debug-enabled specialization.
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // C++23 the formatter is a debug-enabled specialization.
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT __builtin_memcpy isn't constexpr in GCC
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // C++23 the formatter is a debug-enabled specialization.
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.const_char_array.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // C++23 the formatter is a debug-enabled specialization.
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.floating_point.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // [format.formatter.spec]:
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.pointer.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // [format.formatter.spec]:
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.signed_integral.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // [format.formatter.spec]:
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.string.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // C++23 the formatter is a debug-enabled specialization.
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.unsigned_integral.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // [format.formatter.spec]:
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/advance_to.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/advance_to.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/advance_to.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/advance_to.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // constexpr void advance_to(const_iterator it);
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/begin.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/begin.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/begin.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/begin.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // constexpr begin() const noexcept;
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.pass.cpp
@@ -10,7 +10,7 @@
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
 // This test requires the dylib support introduced in D92214.
-// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14|15}}
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
 
 // <format>
 
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.verify.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.verify.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/check_arg_id.verify.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // constexpr void check_arg_id(size_t id);
 
 #include <format>
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/ctor.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/ctor.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/ctor.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // constexpr explicit
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/end.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/end.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/end.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/end.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // constexpr end() const noexcept;
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/next_arg_id.pass.cpp
@@ -10,7 +10,7 @@
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
 // This test requires the dylib support introduced in D92214.
-// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx10.{{9|10|11|12|13|14|15}}
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
 
 // <format>
 
diff --git a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/types.compile.pass.cpp b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/types.compile.pass.cpp
--- a/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/types.compile.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.formatter/format.parse.ctx/types.compile.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // Class typedefs:
diff --git a/libcxx/test/std/utilities/format/format.functions/P2418.pass.cpp b/libcxx/test/std/utilities/format/format.functions/P2418.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/P2418.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/P2418.pass.cpp
@@ -11,6 +11,9 @@
 // Tests whether a move only type can be formatted. This is required by
 // P2418R2 "Add support for std::generator-like types to std::format"
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 #include <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/ascii.pass.cpp b/libcxx/test/std/utilities/format/format.functions/ascii.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/ascii.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/ascii.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Force unicode to be disabled.
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_HAS_NO_UNICODE
 
diff --git a/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp b/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Force unicode to be disabled.
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_HAS_NO_UNICODE
 
diff --git a/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp b/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
@@ -15,6 +15,9 @@
 // UNSUPPORTED: msvc, target={{.+}}-windows-gnu
 // UNSUPPORTED: LIBCXX-AIX-FIXME
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // This test the debug string type for the formatter specializations for char
diff --git a/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp
@@ -11,6 +11,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED:gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class... Args>
diff --git a/libcxx/test/std/utilities/format/format.functions/format.locale.verify.cpp b/libcxx/test/std/utilities/format/format.functions/format.locale.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format.locale.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format.locale.verify.cpp
@@ -9,6 +9,9 @@
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Basic test to validate ill-formed code is properly detected.
 
 // <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/format.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Note this formatter shows additional information when tests are failing.
 // This aids the development. Since other formatters fail in the same fashion
 // they don't have this additional output.
diff --git a/libcxx/test/std/utilities/format/format.functions/format.verify.cpp b/libcxx/test/std/utilities/format/format.functions/format.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format.verify.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Basic test to validate ill-formed code is properly detected.
 
 // <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to.locale.pass.cpp
@@ -11,6 +11,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class Out, class... Args>
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to.locale.verify.cpp b/libcxx/test/std/utilities/format/format.functions/format_to.locale.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to.locale.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to.locale.verify.cpp
@@ -9,6 +9,9 @@
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Basic test to validate ill-formed code is properly detected.
 
 // <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class Out, class... Args>
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to.verify.cpp b/libcxx/test/std/utilities/format/format.functions/format_to.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to.verify.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // Basic test to validate ill-formed code is properly detected.
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.pass.cpp
@@ -11,6 +11,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class Out, class... Args>
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.verify.cpp b/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to_n.locale.verify.cpp
@@ -9,6 +9,9 @@
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Basic test to validate ill-formed code is properly detected.
 
 // <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to_n.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class Out, class... Args>
diff --git a/libcxx/test/std/utilities/format/format.functions/format_to_n.verify.cpp b/libcxx/test/std/utilities/format/format.functions/format_to_n.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format_to_n.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format_to_n.verify.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Basic test to validate ill-formed code is properly detected.
 
 // <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.pass.cpp
@@ -11,6 +11,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class... Args>
diff --git a/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.verify.cpp b/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/formatted_size.locale.verify.cpp
@@ -9,6 +9,9 @@
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Basic test to validate ill-formed code is properly detected.
 
 // <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/formatted_size.pass.cpp b/libcxx/test/std/utilities/format/format.functions/formatted_size.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/formatted_size.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/formatted_size.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class... Args>
diff --git a/libcxx/test/std/utilities/format/format.functions/formatted_size.verify.cpp b/libcxx/test/std/utilities/format/format.functions/formatted_size.verify.cpp
--- a/libcxx/test/std/utilities/format/format.functions/formatted_size.verify.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/formatted_size.verify.cpp
@@ -8,6 +8,9 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: libcpp-has-no-incomplete-format
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // Basic test to validate ill-formed code is properly detected.
 
 // <format>
diff --git a/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp b/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp
@@ -14,6 +14,9 @@
 
 // REQUIRES: locale.en_US.UTF-8
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // This test the locale-specific form for these formatting functions:
diff --git a/libcxx/test/std/utilities/format/format.functions/unicode.pass.cpp b/libcxx/test/std/utilities/format/format.functions/unicode.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/unicode.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/unicode.pass.cpp
@@ -15,6 +15,9 @@
 // UNSUPPORTED msvc, target={{.+}}-windows-gnu
 // UNSUPPORTED: LIBCXX-AIX-FIXME
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // Tests the Unicode width support of the standard format specifiers.
diff --git a/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp
@@ -11,6 +11,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // string vformat(const locale& loc, string_view fmt, format_args args);
diff --git a/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp b/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // string vformat(string_view fmt, format_args args);
diff --git a/libcxx/test/std/utilities/format/format.functions/vformat_to.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/vformat_to.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/vformat_to.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/vformat_to.locale.pass.cpp
@@ -11,6 +11,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class Out>
diff --git a/libcxx/test/std/utilities/format/format.functions/vformat_to.pass.cpp b/libcxx/test/std/utilities/format/format.functions/vformat_to.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/vformat_to.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/vformat_to.pass.cpp
@@ -10,6 +10,9 @@
 // TODO FMT Evaluate gcc-12 status
 // UNSUPPORTED: gcc-12
 
+// This test requires the dylib support introduced in D92214.
+// XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx1{{0|1}}.{{.+}}
+
 // <format>
 
 // template<class Out>
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -451,9 +451,6 @@
     PARAMS+=";unwind_runtime_root=${OSX_ROOTS}/macOS/libunwind/${DEPLOYMENT_TARGET}"
     PARAMS+=";use_system_cxx_lib=True"
     PARAMS+=";enable_assertions=True"
-    # TODO: Enable experimental features during back-deployment -- right now some of the availability
-    #       annotations are incorrect, leading to test failures that could be avoided.
-    PARAMS+=";enable_experimental=False"
 
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Apple.cmake" \
                    -DLIBCXX_TEST_CONFIG="apple-libc++-backdeployment.cfg.in" \