diff --git a/libcxx/include/__locale_dir/support/windows.h b/libcxx/include/__locale_dir/support/windows.h
index 0d3089c150081..4bf7cac4d61f7 100644
--- a/libcxx/include/__locale_dir/support/windows.h
+++ b/libcxx/include/__locale_dir/support/windows.h
@@ -154,6 +154,7 @@ class __locale_t {
 };
 
 #if defined(_LIBCPP_BUILDING_LIBRARY)
+_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_EXPORTED_FROM_ABI __locale_t __newlocale(int __mask, const char* __locale, __locale_t __base);
 inline _LIBCPP_HIDE_FROM_ABI void __freelocale(__locale_t __loc) { ::_free_locale(__loc); }
 inline _LIBCPP_HIDE_FROM_ABI char* __setlocale(int __category, const char* __locale) {
@@ -163,6 +164,7 @@ inline _LIBCPP_HIDE_FROM_ABI char* __setlocale(int __category, const char* __loc
   return __new_locale;
 }
 _LIBCPP_EXPORTED_FROM_ABI __lconv_t* __localeconv(__locale_t& __loc);
+_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 #endif // _LIBCPP_BUILDING_LIBRARY
 
 //
@@ -178,8 +180,10 @@ inline _LIBCPP_HIDE_FROM_ABI long double __strtold(const char* __nptr, char** __
   return ::_strtold_l(__nptr, __endptr, __loc);
 }
 #else
+_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_EXPORTED_FROM_ABI float __strtof(const char*, char**, __locale_t);
 _LIBCPP_EXPORTED_FROM_ABI long double __strtold(const char*, char**, __locale_t);
+_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 #endif
 
 inline _LIBCPP_HIDE_FROM_ABI double __strtod(const char* __nptr, char** __endptr, __locale_t __loc) {
@@ -280,11 +284,13 @@ _LIBCPP_EXPORTED_FROM_ABI size_t
 __mbsrtowcs(wchar_t* __restrict, const char** __restrict, size_t, mbstate_t* __restrict, __locale_t);
 #endif // _LIBCPP_BUILDING_LIBRARY
 
+_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 4, 5) int __snprintf(
     char* __ret, size_t __n, __locale_t __loc, const char* __format, ...);
 
 _LIBCPP_EXPORTED_FROM_ABI
 _LIBCPP_ATTRIBUTE_FORMAT(__printf__, 3, 4) int __asprintf(char** __ret, __locale_t __loc, const char* __format, ...);
+_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 
 _LIBCPP_DIAGNOSTIC_PUSH
 _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wgcc-compat")
diff --git a/libcxx/include/__thread/support/windows.h b/libcxx/include/__thread/support/windows.h
index 5dc4fa14f45b6..9e2d62ec72050 100644
--- a/libcxx/include/__thread/support/windows.h
+++ b/libcxx/include/__thread/support/windows.h
@@ -19,6 +19,7 @@
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
 using __libcpp_timespec_t = ::timespec;
 
@@ -128,6 +129,7 @@ _LIBCPP_EXPORTED_FROM_ABI void* __libcpp_tls_get(__libcpp_tls_key __key);
 
 _LIBCPP_EXPORTED_FROM_ABI int __libcpp_tls_set(__libcpp_tls_key __key, void* __p);
 
+_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP___THREAD_SUPPORT_WINDOWS_H
diff --git a/libcxx/src/support/win32/locale_win32.cpp b/libcxx/src/support/win32/locale_win32.cpp
index 24402e818d95d..f326983ab8977 100644
--- a/libcxx/src/support/win32/locale_win32.cpp
+++ b/libcxx/src/support/win32/locale_win32.cpp
@@ -16,6 +16,7 @@
 #include <cwchar>  // wide char manipulation
 
 _LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 namespace __locale {
 
 //
@@ -182,4 +183,5 @@ int __asprintf(char** ret, __locale_t loc, const char* format, ...) {
 }
 
 } // namespace __locale
+_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/src/support/win32/thread_win32.cpp b/libcxx/src/support/win32/thread_win32.cpp
index 3a67d759f0f5e..606104e32b453 100644
--- a/libcxx/src/support/win32/thread_win32.cpp
+++ b/libcxx/src/support/win32/thread_win32.cpp
@@ -16,6 +16,7 @@
 #include <fibersapi.h>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
+_LIBCPP_BEGIN_EXPLICIT_ABI_ANNOTATIONS
 
 static_assert(sizeof(__libcpp_mutex_t) == sizeof(SRWLOCK), "");
 static_assert(alignof(__libcpp_mutex_t) == alignof(SRWLOCK), "");
@@ -211,4 +212,5 @@ int __libcpp_tls_set(__libcpp_tls_key __key, void* __p) {
   return 0;
 }
 
+_LIBCPP_END_EXPLICIT_ABI_ANNOTATIONS
 _LIBCPP_END_NAMESPACE_STD