diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -222,8 +222,6 @@
   __bit/popcount.h
   __bit/rotate.h
   __bit_reference
-  __bsd_locale_defaults.h
-  __bsd_locale_fallbacks.h
   __charconv/chars_format.h
   __charconv/from_chars_integral.h
   __charconv/from_chars_result.h
@@ -589,6 +587,8 @@
   __support/xlocale/__nop_locale_mgmt.h
   __support/xlocale/__posix_l_fallback.h
   __support/xlocale/__strtonum_fallback.h
+  __support/xlocale/bsd_locale_defaults.h
+  __support/xlocale/bsd_locale_fallbacks.h
   __thread/poll_with_backoff.h
   __thread/timed_backoff_policy.h
   __threading_support
diff --git a/libcxx/include/__locale b/libcxx/include/__locale
--- a/libcxx/include/__locale
+++ b/libcxx/include/__locale
@@ -52,63 +52,6 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if !defined(_LIBCPP_LOCALE__L_EXTENSIONS)
-struct __libcpp_locale_guard {
-  _LIBCPP_INLINE_VISIBILITY
-  __libcpp_locale_guard(locale_t& __loc) : __old_loc_(uselocale(__loc)) {}
-
-  _LIBCPP_INLINE_VISIBILITY
-  ~__libcpp_locale_guard() {
-    if (__old_loc_)
-      uselocale(__old_loc_);
-  }
-
-  locale_t __old_loc_;
-private:
-  __libcpp_locale_guard(__libcpp_locale_guard const&);
-  __libcpp_locale_guard& operator=(__libcpp_locale_guard const&);
-};
-#elif defined(_LIBCPP_MSVCRT_LIKE)
-struct __libcpp_locale_guard {
-    __libcpp_locale_guard(locale_t __l) :
-        __status(_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)) {
-      // Setting the locale can be expensive even when the locale given is
-      // already the current locale, so do an explicit check to see if the
-      // current locale is already the one we want.
-      const char* __lc = __setlocale(nullptr);
-      // If every category is the same, the locale string will simply be the
-      // locale name, otherwise it will be a semicolon-separated string listing
-      // each category.  In the second case, we know at least one category won't
-      // be what we want, so we only have to check the first case.
-      if (_VSTD::strcmp(__l.__get_locale(), __lc) != 0) {
-        __locale_all = _strdup(__lc);
-        if (__locale_all == nullptr)
-          __throw_bad_alloc();
-        __setlocale(__l.__get_locale());
-      }
-    }
-    ~__libcpp_locale_guard() {
-      // The CRT documentation doesn't explicitly say, but setlocale() does the
-      // right thing when given a semicolon-separated list of locale settings
-      // for the different categories in the same format as returned by
-      // setlocale(LC_ALL, nullptr).
-      if (__locale_all != nullptr) {
-        __setlocale(__locale_all);
-        free(__locale_all);
-      }
-      _configthreadlocale(__status);
-    }
-    static const char* __setlocale(const char* __locale) {
-      const char* __new_locale = setlocale(LC_ALL, __locale);
-      if (__new_locale == nullptr)
-        __throw_bad_alloc();
-      return __new_locale;
-    }
-    int __status;
-    char* __locale_all = nullptr;
-};
-#endif
-
 class _LIBCPP_TYPE_VIS locale;
 
 template <class _Facet>
diff --git a/libcxx/include/__bsd_locale_defaults.h b/libcxx/include/__support/xlocale/bsd_locale_defaults.h
rename from libcxx/include/__bsd_locale_defaults.h
rename to libcxx/include/__support/xlocale/bsd_locale_defaults.h
--- a/libcxx/include/__bsd_locale_defaults.h
+++ b/libcxx/include/__support/xlocale/bsd_locale_defaults.h
@@ -11,8 +11,8 @@
 // we will define the mapping from an internal macro to the real BSD symbol.
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___BSD_LOCALE_DEFAULTS_H
-#define _LIBCPP___BSD_LOCALE_DEFAULTS_H
+#ifndef _LIBCPP___SUPPORT_XLOCALE_BSD_LOCALE_DEFAULTS_H
+#define _LIBCPP___SUPPORT_XLOCALE_BSD_LOCALE_DEFAULTS_H
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -33,4 +33,4 @@
 #define __libcpp_asprintf_l(...)                            asprintf_l(__VA_ARGS__)
 #define __libcpp_sscanf_l(...)                              sscanf_l(__VA_ARGS__)
 
-#endif // _LIBCPP___BSD_LOCALE_DEFAULTS_H
+#endif // _LIBCPP___SUPPORT_XLOCALE_BSD_LOCALE_DEFAULTS_H
diff --git a/libcxx/include/__bsd_locale_fallbacks.h b/libcxx/include/__support/xlocale/bsd_locale_fallbacks.h
rename from libcxx/include/__bsd_locale_fallbacks.h
rename to libcxx/include/__support/xlocale/bsd_locale_fallbacks.h
--- a/libcxx/include/__bsd_locale_fallbacks.h
+++ b/libcxx/include/__support/xlocale/bsd_locale_fallbacks.h
@@ -10,9 +10,12 @@
 // of those functions for non-BSD platforms.
 //===----------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___BSD_LOCALE_FALLBACKS_H
-#define _LIBCPP___BSD_LOCALE_FALLBACKS_H
+#ifndef _LIBCPP___SUPPORT_XLOCALE_BSD_LOCALE_FALLBACKS_H
+#define _LIBCPP___SUPPORT_XLOCALE_BSD_LOCALE_FALLBACKS_H
 
+#include <clocale>
+#include <cstdio>
+#include <cwchar>
 #include <stdarg.h>
 #include <stdlib.h>
 
@@ -22,6 +25,62 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#if !defined(_LIBCPP_LOCALE__L_EXTENSIONS)
+struct __libcpp_locale_guard {
+  _LIBCPP_INLINE_VISIBILITY __libcpp_locale_guard(locale_t& __loc) : __old_loc_(uselocale(__loc)) {}
+
+  _LIBCPP_INLINE_VISIBILITY ~__libcpp_locale_guard() {
+    if (__old_loc_)
+      uselocale(__old_loc_);
+  }
+
+  locale_t __old_loc_;
+
+private:
+  __libcpp_locale_guard(__libcpp_locale_guard const&);
+  __libcpp_locale_guard& operator=(__libcpp_locale_guard const&);
+};
+#elif defined(_LIBCPP_MSVCRT_LIKE)
+struct __libcpp_locale_guard {
+    __libcpp_locale_guard(locale_t __l) :
+        __status(_configthreadlocale(_ENABLE_PER_THREAD_LOCALE)) {
+      // Setting the locale can be expensive even when the locale given is
+      // already the current locale, so do an explicit check to see if the
+      // current locale is already the one we want.
+      const char* __lc = __setlocale(nullptr);
+      // If every category is the same, the locale string will simply be the
+      // locale name, otherwise it will be a semicolon-separated string listing
+      // each category.  In the second case, we know at least one category won't
+      // be what we want, so we only have to check the first case.
+      if (_VSTD::strcmp(__l.__get_locale(), __lc) != 0) {
+        __locale_all = _strdup(__lc);
+        if (__locale_all == nullptr)
+          __throw_bad_alloc();
+        __setlocale(__l.__get_locale());
+      }
+    }
+    ~__libcpp_locale_guard() {
+      // The CRT documentation doesn't explicitly say, but setlocale() does the
+      // right thing when given a semicolon-separated list of locale settings
+      // for the different categories in the same format as returned by
+      // setlocale(LC_ALL, nullptr).
+      if (__locale_all != nullptr) {
+        __setlocale(__locale_all);
+        free(__locale_all);
+      }
+      _configthreadlocale(__status);
+    }
+    static const char* __setlocale(const char* __locale) {
+      const char* __new_locale = setlocale(LC_ALL, __locale);
+      if (__new_locale == nullptr)
+        __throw_bad_alloc();
+      return __new_locale;
+    }
+    int __status;
+    char* __locale_all = nullptr;
+};
+#endif
+
 inline _LIBCPP_INLINE_VISIBILITY
 decltype(MB_CUR_MAX) __libcpp_mb_cur_max_l(locale_t __l)
 {
@@ -139,4 +198,4 @@
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP___BSD_LOCALE_FALLBACKS_H
+#endif // _LIBCPP___SUPPORT_XLOCALE_BSD_LOCALE_FALLBACKS_H
diff --git a/libcxx/include/locale b/libcxx/include/locale
--- a/libcxx/include/locale
+++ b/libcxx/include/locale
@@ -224,9 +224,9 @@
 #endif
 
 #ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-#include <__bsd_locale_defaults.h>
+#  include <__support/xlocale/bsd_locale_defaults.h>
 #else
-#include <__bsd_locale_fallbacks.h>
+#  include <__support/xlocale/bsd_locale_fallbacks.h>
 #endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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
@@ -493,6 +493,7 @@
 list version
 locale atomic
 locale cctype
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
@@ -501,6 +502,7 @@
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
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
@@ -493,6 +493,7 @@
 list version
 locale atomic
 locale cctype
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
@@ -501,6 +502,7 @@
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
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
@@ -495,6 +495,7 @@
 list version
 locale atomic
 locale cctype
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
@@ -503,6 +504,7 @@
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
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
@@ -495,6 +495,7 @@
 list version
 locale atomic
 locale cctype
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
@@ -503,6 +504,7 @@
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
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
@@ -501,6 +501,7 @@
 list version
 locale atomic
 locale cctype
+locale clocale
 locale concepts
 locale cstdarg
 locale cstddef
@@ -509,6 +510,7 @@
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
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
@@ -351,12 +351,14 @@
 list tuple
 list version
 locale cctype
+locale clocale
 locale cstddef
 locale cstdint
 locale cstdio
 locale cstdlib
 locale cstring
 locale ctime
+locale cwchar
 locale initializer_list
 locale ios
 locale iosfwd
diff --git a/libcxx/utils/data/ignore_format.txt b/libcxx/utils/data/ignore_format.txt
--- a/libcxx/utils/data/ignore_format.txt
+++ b/libcxx/utils/data/ignore_format.txt
@@ -236,8 +236,6 @@
 libcxx/include/__bit_reference
 libcxx/include/__bit/rotate.h
 libcxx/include/bitset
-libcxx/include/__bsd_locale_defaults.h
-libcxx/include/__bsd_locale_fallbacks.h
 libcxx/include/cctype
 libcxx/include/chrono
 libcxx/include/__chrono/calendar.h
@@ -611,6 +609,8 @@
 libcxx/include/__support/newlib/xlocale.h
 libcxx/include/__support/solaris/xlocale.h
 libcxx/include/__support/win32/locale_win32.h
+libcxx/include/__support/bsd_locale_defaults.h
+libcxx/include/__support/bsd_locale_fallbacks.h
 libcxx/include/__support/xlocale/__nop_locale_mgmt.h
 libcxx/include/system_error
 libcxx/include/thread