diff --git a/libcxx/include/__chrono/formatter.h b/libcxx/include/__chrono/formatter.h
index 449c415e95760..ff2593f723029 100644
--- a/libcxx/include/__chrono/formatter.h
+++ b/libcxx/include/__chrono/formatter.h
@@ -10,55 +10,58 @@
 #ifndef _LIBCPP___CHRONO_FORMATTER_H
 #define _LIBCPP___CHRONO_FORMATTER_H
 
-#include <__algorithm/ranges_copy.h>
-#include <__chrono/calendar.h>
-#include <__chrono/concepts.h>
-#include <__chrono/convert_to_tm.h>
-#include <__chrono/day.h>
-#include <__chrono/duration.h>
-#include <__chrono/file_clock.h>
-#include <__chrono/hh_mm_ss.h>
-#include <__chrono/local_info.h>
-#include <__chrono/month.h>
-#include <__chrono/month_weekday.h>
-#include <__chrono/monthday.h>
-#include <__chrono/ostream.h>
-#include <__chrono/parser_std_format_spec.h>
-#include <__chrono/statically_widen.h>
-#include <__chrono/sys_info.h>
-#include <__chrono/system_clock.h>
-#include <__chrono/time_point.h>
-#include <__chrono/weekday.h>
-#include <__chrono/year.h>
-#include <__chrono/year_month.h>
-#include <__chrono/year_month_day.h>
-#include <__chrono/year_month_weekday.h>
-#include <__chrono/zoned_time.h>
-#include <__concepts/arithmetic.h>
-#include <__concepts/same_as.h>
 #include <__config>
-#include <__format/concepts.h>
-#include <__format/format_error.h>
-#include <__format/format_functions.h>
-#include <__format/format_parse_context.h>
-#include <__format/formatter.h>
-#include <__format/parser_std_format_spec.h>
-#include <__format/write_escaped.h>
-#include <__memory/addressof.h>
-#include <__type_traits/is_specialization.h>
-#include <cmath>
-#include <ctime>
-#include <limits>
-#include <sstream>
-#include <string_view>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+
+#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+
+#  include <__algorithm/ranges_copy.h>
+#  include <__chrono/calendar.h>
+#  include <__chrono/concepts.h>
+#  include <__chrono/convert_to_tm.h>
+#  include <__chrono/day.h>
+#  include <__chrono/duration.h>
+#  include <__chrono/file_clock.h>
+#  include <__chrono/hh_mm_ss.h>
+#  include <__chrono/local_info.h>
+#  include <__chrono/month.h>
+#  include <__chrono/month_weekday.h>
+#  include <__chrono/monthday.h>
+#  include <__chrono/ostream.h>
+#  include <__chrono/parser_std_format_spec.h>
+#  include <__chrono/statically_widen.h>
+#  include <__chrono/sys_info.h>
+#  include <__chrono/system_clock.h>
+#  include <__chrono/time_point.h>
+#  include <__chrono/weekday.h>
+#  include <__chrono/year.h>
+#  include <__chrono/year_month.h>
+#  include <__chrono/year_month_day.h>
+#  include <__chrono/year_month_weekday.h>
+#  include <__chrono/zoned_time.h>
+#  include <__concepts/arithmetic.h>
+#  include <__concepts/same_as.h>
+#  include <__format/concepts.h>
+#  include <__format/format_error.h>
+#  include <__format/format_functions.h>
+#  include <__format/format_parse_context.h>
+#  include <__format/formatter.h>
+#  include <__format/parser_std_format_spec.h>
+#  include <__format/write_escaped.h>
+#  include <__memory/addressof.h>
+#  include <__type_traits/is_specialization.h>
+#  include <cmath>
+#  include <ctime>
+#  include <limits>
+#  include <sstream>
+#  include <string_view>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 
 namespace __formatter {
 
@@ -139,24 +142,24 @@ __format_sub_seconds(basic_stringstream<_CharT>& __sstr, const chrono::hh_mm_ss<
                    __value.fractional_width);
 }
 
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB) && !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) &&                     \
-      !defined(_LIBCPP_HAS_NO_FILESYSTEM) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB) && !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) &&                   \
+        !defined(_LIBCPP_HAS_NO_FILESYSTEM)
 template <class _CharT, class _Duration, class _TimeZonePtr>
 _LIBCPP_HIDE_FROM_ABI void
 __format_sub_seconds(basic_stringstream<_CharT>& __sstr, const chrono::zoned_time<_Duration, _TimeZonePtr>& __value) {
   __formatter::__format_sub_seconds(__sstr, __value.get_local_time().time_since_epoch());
 }
-#  endif
+#    endif
 
 template <class _Tp>
 consteval bool __use_fraction() {
   if constexpr (__is_time_point<_Tp>)
     return chrono::hh_mm_ss<typename _Tp::duration>::fractional_width;
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB) && !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) &&                     \
-      !defined(_LIBCPP_HAS_NO_FILESYSTEM) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB) && !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) &&                   \
+        !defined(_LIBCPP_HAS_NO_FILESYSTEM)
   else if constexpr (__is_specialization_v<_Tp, chrono::zoned_time>)
     return chrono::hh_mm_ss<typename _Tp::duration>::fractional_width;
-#  endif
+#    endif
   else if constexpr (chrono::__is_duration<_Tp>::value)
     return chrono::hh_mm_ss<_Tp>::fractional_width;
   else if constexpr (__is_hh_mm_ss<_Tp>)
@@ -225,16 +228,15 @@ struct _LIBCPP_HIDE_FROM_ABI __time_zone {
 
 template <class _Tp>
 _LIBCPP_HIDE_FROM_ABI __time_zone __convert_to_time_zone([[maybe_unused]] const _Tp& __value) {
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   if constexpr (same_as<_Tp, chrono::sys_info>)
     return {__value.abbrev, __value.offset};
-#    if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                          \
-        !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#      if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
   else if constexpr (__is_specialization_v<_Tp, chrono::zoned_time>)
     return __formatter::__convert_to_time_zone(__value.get_info());
-#    endif
+#      endif
   else
-#  endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
     return {"UTC", chrono::seconds{0}};
 }
 
@@ -341,12 +343,12 @@ _LIBCPP_HIDE_FROM_ABI void __format_chrono_using_chrono_specs(
         //
         // TODO FMT evaluate the comment above.
 
-#  if defined(__GLIBC__) || defined(_AIX) || defined(_WIN32)
+#    if defined(__GLIBC__) || defined(_AIX) || defined(_WIN32)
       case _CharT('y'):
         // Glibc fails for negative values, AIX for positive values too.
         __sstr << std::format(_LIBCPP_STATICALLY_WIDEN(_CharT, "{:02}"), (std::abs(__t.tm_year + 1900)) % 100);
         break;
-#  endif // defined(__GLIBC__) || defined(_AIX) || defined(_WIN32)
+#    endif // defined(__GLIBC__) || defined(_AIX) || defined(_WIN32)
 
       case _CharT('Y'):
         // Depending on the platform's libc the range of supported years is
@@ -442,17 +444,16 @@ _LIBCPP_HIDE_FROM_ABI constexpr bool __weekday_ok(const _Tp& __value) {
     return __value.weekday().ok();
   else if constexpr (__is_hh_mm_ss<_Tp>)
     return true;
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else if constexpr (same_as<_Tp, chrono::sys_info>)
     return true;
   else if constexpr (same_as<_Tp, chrono::local_info>)
     return true;
-#    if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                          \
-        !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#      if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
   else if constexpr (__is_specialization_v<_Tp, chrono::zoned_time>)
     return true;
-#    endif
-#  endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#      endif
+#    endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else
     static_assert(sizeof(_Tp) == 0, "Add the missing type specialization");
 }
@@ -493,17 +494,16 @@ _LIBCPP_HIDE_FROM_ABI constexpr bool __weekday_name_ok(const _Tp& __value) {
     return __value.weekday().ok();
   else if constexpr (__is_hh_mm_ss<_Tp>)
     return true;
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else if constexpr (same_as<_Tp, chrono::sys_info>)
     return true;
   else if constexpr (same_as<_Tp, chrono::local_info>)
     return true;
-#    if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                          \
-        !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#      if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
   else if constexpr (__is_specialization_v<_Tp, chrono::zoned_time>)
     return true;
-#    endif
-#  endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#      endif
+#    endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else
     static_assert(sizeof(_Tp) == 0, "Add the missing type specialization");
 }
@@ -544,17 +544,16 @@ _LIBCPP_HIDE_FROM_ABI constexpr bool __date_ok(const _Tp& __value) {
     return __value.ok();
   else if constexpr (__is_hh_mm_ss<_Tp>)
     return true;
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else if constexpr (same_as<_Tp, chrono::sys_info>)
     return true;
   else if constexpr (same_as<_Tp, chrono::local_info>)
     return true;
-#    if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                          \
-        !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#      if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
   else if constexpr (__is_specialization_v<_Tp, chrono::zoned_time>)
     return true;
-#    endif
-#  endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#      endif
+#    endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else
     static_assert(sizeof(_Tp) == 0, "Add the missing type specialization");
 }
@@ -595,17 +594,16 @@ _LIBCPP_HIDE_FROM_ABI constexpr bool __month_name_ok(const _Tp& __value) {
     return __value.month().ok();
   else if constexpr (__is_hh_mm_ss<_Tp>)
     return true;
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else if constexpr (same_as<_Tp, chrono::sys_info>)
     return true;
   else if constexpr (same_as<_Tp, chrono::local_info>)
     return true;
-#    if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                          \
-        !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#      if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
   else if constexpr (__is_specialization_v<_Tp, chrono::zoned_time>)
     return true;
-#    endif
-#  endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#      endif
+#    endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
   else
     static_assert(sizeof(_Tp) == 0, "Add the missing type specialization");
 }
@@ -943,7 +941,7 @@ struct formatter<chrono::hh_mm_ss<_Duration>, _CharT> : public __formatter_chron
   }
 };
 
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
 template <__fmt_char_type _CharT>
 struct formatter<chrono::sys_info, _CharT> : public __formatter_chrono<_CharT> {
 public:
@@ -965,8 +963,7 @@ struct formatter<chrono::local_info, _CharT> : public __formatter_chrono<_CharT>
     return _Base::__parse(__ctx, __format_spec::__fields_chrono, __format_spec::__flags{});
   }
 };
-#    if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                          \
-        !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#      if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
 // Note due to how libc++'s formatters are implemented there is no need to add
 // the exposition only local-time-format-t abstraction.
 template <class _Duration, class _TimeZonePtr, __fmt_char_type _CharT>
@@ -979,12 +976,13 @@ struct formatter<chrono::zoned_time<_Duration, _TimeZonePtr>, _CharT> : public _
     return _Base::__parse(__ctx, __format_spec::__fields_chrono, __format_spec::__flags::__clock);
   }
 };
-#    endif // !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&
-           // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
-#  endif   // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#      endif // !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
+#    endif   // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
 
-#endif // if _LIBCPP_STD_VER >= 20
+#  endif // if _LIBCPP_STD_VER >= 20
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !_LIBCPP_HAS_NO_LOCALIZATION
+
 #endif //  _LIBCPP___CHRONO_FORMATTER_H
diff --git a/libcxx/include/__chrono/ostream.h b/libcxx/include/__chrono/ostream.h
index e6c43254eea15..196ebd518541c 100644
--- a/libcxx/include/__chrono/ostream.h
+++ b/libcxx/include/__chrono/ostream.h
@@ -10,37 +10,40 @@
 #ifndef _LIBCPP___CHRONO_OSTREAM_H
 #define _LIBCPP___CHRONO_OSTREAM_H
 
-#include <__chrono/calendar.h>
-#include <__chrono/day.h>
-#include <__chrono/duration.h>
-#include <__chrono/file_clock.h>
-#include <__chrono/hh_mm_ss.h>
-#include <__chrono/local_info.h>
-#include <__chrono/month.h>
-#include <__chrono/month_weekday.h>
-#include <__chrono/monthday.h>
-#include <__chrono/statically_widen.h>
-#include <__chrono/sys_info.h>
-#include <__chrono/system_clock.h>
-#include <__chrono/weekday.h>
-#include <__chrono/year.h>
-#include <__chrono/year_month.h>
-#include <__chrono/year_month_day.h>
-#include <__chrono/year_month_weekday.h>
-#include <__chrono/zoned_time.h>
-#include <__concepts/same_as.h>
 #include <__config>
-#include <__format/format_functions.h>
-#include <__fwd/ostream.h>
-#include <ratio>
 
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+
+#  include <__chrono/calendar.h>
+#  include <__chrono/day.h>
+#  include <__chrono/duration.h>
+#  include <__chrono/file_clock.h>
+#  include <__chrono/hh_mm_ss.h>
+#  include <__chrono/local_info.h>
+#  include <__chrono/month.h>
+#  include <__chrono/month_weekday.h>
+#  include <__chrono/monthday.h>
+#  include <__chrono/statically_widen.h>
+#  include <__chrono/sys_info.h>
+#  include <__chrono/system_clock.h>
+#  include <__chrono/weekday.h>
+#  include <__chrono/year.h>
+#  include <__chrono/year_month.h>
+#  include <__chrono/year_month_day.h>
+#  include <__chrono/year_month_weekday.h>
+#  include <__chrono/zoned_time.h>
+#  include <__concepts/same_as.h>
+#  include <__format/format_functions.h>
+#  include <__fwd/ostream.h>
+#  include <ratio>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 
 namespace chrono {
 
@@ -82,11 +85,11 @@ _LIBCPP_HIDE_FROM_ABI auto __units_suffix() {
   else if constexpr (same_as<typename _Period::type, nano>)
     return _LIBCPP_STATICALLY_WIDEN(_CharT, "ns");
   else if constexpr (same_as<typename _Period::type, micro>)
-#  ifndef _LIBCPP_HAS_NO_UNICODE
+#    ifndef _LIBCPP_HAS_NO_UNICODE
     return _LIBCPP_STATICALLY_WIDEN(_CharT, "\u00b5s");
-#  else
+#    else
     return _LIBCPP_STATICALLY_WIDEN(_CharT, "us");
-#  endif
+#    endif
   else if constexpr (same_as<typename _Period::type, milli>)
     return _LIBCPP_STATICALLY_WIDEN(_CharT, "ms");
   else if constexpr (same_as<typename _Period::type, centi>)
@@ -265,7 +268,7 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const hh_mm_ss<_Duration> __hms
   return __os << std::format(__os.getloc(), _LIBCPP_STATICALLY_WIDEN(_CharT, "{:L%T}"), __hms);
 }
 
-#  if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#    if !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
 
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
@@ -303,20 +306,21 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const local_info& __info) {
              _LIBCPP_STATICALLY_WIDEN(_CharT, "{}: {{{}, {}}}"), __result(), __info.first, __info.second);
 }
 
-#    if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&                          \
-        !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#      if !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM)
 template <class _CharT, class _Traits, class _Duration, class _TimeZonePtr>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, const zoned_time<_Duration, _TimeZonePtr>& __tp) {
   return __os << std::format(__os.getloc(), _LIBCPP_STATICALLY_WIDEN(_CharT, "{:L%F %T %Z}"), __tp);
 }
-#    endif
-#  endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
+#      endif
+#    endif // !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_TZDB)
 
 } // namespace chrono
 
-#endif // if _LIBCPP_STD_VER >= 20
+#  endif // if _LIBCPP_STD_VER >= 20
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !_LIBCPP_HAS_NO_LOCALIZATION
+
 #endif // _LIBCPP___CHRONO_OSTREAM_H
diff --git a/libcxx/include/__chrono/parser_std_format_spec.h b/libcxx/include/__chrono/parser_std_format_spec.h
index 6803d03ad882f..c9cfcc6d572f4 100644
--- a/libcxx/include/__chrono/parser_std_format_spec.h
+++ b/libcxx/include/__chrono/parser_std_format_spec.h
@@ -11,20 +11,23 @@
 #define _LIBCPP___CHRONO_PARSER_STD_FORMAT_SPEC_H
 
 #include <__config>
-#include <__format/concepts.h>
-#include <__format/format_error.h>
-#include <__format/format_parse_context.h>
-#include <__format/formatter_string.h>
-#include <__format/parser_std_format_spec.h>
-#include <string_view>
 
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
+#  include <__format/concepts.h>
+#  include <__format/format_error.h>
+#  include <__format/format_parse_context.h>
+#  include <__format/formatter_string.h>
+#  include <__format/parser_std_format_spec.h>
+#  include <string_view>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 
 namespace __format_spec {
 
@@ -409,8 +412,10 @@ class _LIBCPP_TEMPLATE_VIS __parser_chrono {
 
 } // namespace __format_spec
 
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
 #endif // _LIBCPP___CHRONO_PARSER_STD_FORMAT_SPEC_H
diff --git a/libcxx/include/__ostream/basic_ostream.h b/libcxx/include/__ostream/basic_ostream.h
index e0698ccb4842a..1f7fe8338c589 100644
--- a/libcxx/include/__ostream/basic_ostream.h
+++ b/libcxx/include/__ostream/basic_ostream.h
@@ -10,29 +10,32 @@
 #define _LIBCPP___OSTREAM_BASIC_OSTREAM_H
 
 #include <__config>
-#include <__exception/operations.h>
-#include <__memory/shared_ptr.h>
-#include <__memory/unique_ptr.h>
-#include <__system_error/error_code.h>
-#include <__type_traits/conjunction.h>
-#include <__type_traits/enable_if.h>
-#include <__type_traits/is_base_of.h>
-#include <__type_traits/void_t.h>
-#include <__utility/declval.h>
-#include <bitset>
-#include <cstddef>
-#include <ios>
-#include <locale>
-#include <new> // for __throw_bad_alloc
-#include <streambuf>
-#include <string_view>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
+#  include <__exception/operations.h>
+#  include <__memory/shared_ptr.h>
+#  include <__memory/unique_ptr.h>
+#  include <__system_error/error_code.h>
+#  include <__type_traits/conjunction.h>
+#  include <__type_traits/enable_if.h>
+#  include <__type_traits/is_base_of.h>
+#  include <__type_traits/void_t.h>
+#  include <__utility/declval.h>
+#  include <bitset>
+#  include <cstddef>
+#  include <ios>
+#  include <locale>
+#  include <new> // for __throw_bad_alloc
+#  include <streambuf>
+#  include <string_view>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_PUSH_MACROS
-#include <__undef_macros>
+#  include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -99,19 +102,19 @@ class _LIBCPP_TEMPLATE_VIS basic_ostream : virtual public basic_ios<_CharT, _Tra
   basic_ostream& operator<<(long double __f);
   basic_ostream& operator<<(const void* __p);
 
-#if _LIBCPP_STD_VER >= 23
+#  if _LIBCPP_STD_VER >= 23
   _LIBCPP_HIDE_FROM_ABI basic_ostream& operator<<(const volatile void* __p) {
     return operator<<(const_cast<const void*>(__p));
   }
-#endif
+#  endif
 
   basic_ostream& operator<<(basic_streambuf<char_type, traits_type>* __sb);
 
-#if _LIBCPP_STD_VER >= 17
+#  if _LIBCPP_STD_VER >= 17
   // LWG 2221 - nullptr. This is not backported to older standards modes.
   // See https://reviews.llvm.org/D127033 for more info on the rationale.
   _LIBCPP_HIDE_FROM_ABI basic_ostream& operator<<(nullptr_t) { return *this << "nullptr"; }
-#endif
+#  endif
 
   // 27.7.2.7 Unformatted output:
   basic_ostream& put(char_type __c);
@@ -153,15 +156,15 @@ basic_ostream<_CharT, _Traits>::sentry::sentry(basic_ostream<_CharT, _Traits>& _
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>::sentry::~sentry() {
   if (__os_.rdbuf() && __os_.good() && (__os_.flags() & ios_base::unitbuf) && uncaught_exceptions() == 0) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       if (__os_.rdbuf()->pubsync() == -1)
         __os_.setstate(ios_base::badbit);
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   }
 }
 
@@ -182,15 +185,15 @@ basic_ostream<_CharT, _Traits>::~basic_ostream() {}
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>&
 basic_ostream<_CharT, _Traits>::operator<<(basic_streambuf<char_type, traits_type>* __sb) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       if (__sb) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
         try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
           typedef istreambuf_iterator<_CharT, _Traits> _Ip;
           typedef ostreambuf_iterator<_CharT, _Traits> _Op;
           _Ip __i(__sb);
@@ -204,27 +207,27 @@ basic_ostream<_CharT, _Traits>::operator<<(basic_streambuf<char_type, traits_typ
           }
           if (__c == 0)
             this->setstate(ios_base::failbit);
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
         } catch (...) {
           this->__set_failbit_and_consider_rethrow();
         }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       } else
         this->setstate(ios_base::badbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(bool __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -232,19 +235,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(bool
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(short __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       ios_base::fmtflags __flags = ios_base::flags() & ios_base::basefield;
@@ -259,19 +262,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(short
               .failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsigned short __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -279,19 +282,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsig
       if (__f.put(*this, *this, this->fill(), static_cast<unsigned long>(__n)).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(int __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       ios_base::fmtflags __flags = ios_base::flags() & ios_base::basefield;
@@ -306,19 +309,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(int _
               .failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsigned int __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -326,19 +329,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsig
       if (__f.put(*this, *this, this->fill(), static_cast<unsigned long>(__n)).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(long __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -346,19 +349,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(long
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsigned long __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -366,19 +369,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsig
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(long long __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -386,19 +389,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(long
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsigned long long __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -406,19 +409,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(unsig
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(float __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -426,19 +429,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(float
       if (__f.put(*this, *this, this->fill(), static_cast<double>(__n)).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(double __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -446,19 +449,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(doubl
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(long double __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -466,19 +469,19 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(long
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(const void* __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef num_put<char_type, ostreambuf_iterator<char_type, traits_type> > _Fp;
@@ -486,20 +489,20 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::operator<<(const
       if (__f.put(*this, *this, this->fill(), __n).failed())
         this->setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 __put_character_sequence(basic_ostream<_CharT, _Traits>& __os, const _CharT* __str, size_t __len) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     typename basic_ostream<_CharT, _Traits>::sentry __s(__os);
     if (__s) {
       typedef ostreambuf_iterator<_CharT, _Traits> _Ip;
@@ -513,11 +516,11 @@ __put_character_sequence(basic_ostream<_CharT, _Traits>& __os, const _CharT* __s
               .failed())
         __os.setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __os.__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return __os;
 }
 
@@ -528,9 +531,9 @@ _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& operator<<(basic_ostream<_
 
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& operator<<(basic_ostream<_CharT, _Traits>& __os, char __cn) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     typename basic_ostream<_CharT, _Traits>::sentry __s(__os);
     if (__s) {
       _CharT __c = __os.widen(__cn);
@@ -545,11 +548,11 @@ _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>& operator<<(basic_ostream<_
               .failed())
         __os.setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __os.__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return __os;
 }
 
@@ -577,9 +580,9 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const _CharT* __str) {
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, const char* __strn) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     typename basic_ostream<_CharT, _Traits>::sentry __s(__os);
     if (__s) {
       typedef ostreambuf_iterator<_CharT, _Traits> _Ip;
@@ -606,11 +609,11 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const char* __strn) {
               .failed())
         __os.setstate(ios_base::badbit | ios_base::failbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __os.__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return __os;
 }
 
@@ -635,9 +638,9 @@ operator<<(basic_ostream<char, _Traits>& __os, const unsigned char* __str) {
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::put(char_type __c) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __s(*this);
     if (__s) {
       typedef ostreambuf_iterator<_CharT, _Traits> _Op;
@@ -646,37 +649,37 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::put(char_type __
       if (__o.failed())
         this->setstate(ios_base::badbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::write(const char_type* __s, streamsize __n) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     sentry __sen(*this);
     if (__sen && __n) {
       if (this->rdbuf()->sputn(__s, __n) != __n)
         this->setstate(ios_base::badbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
 template <class _CharT, class _Traits>
 basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::flush() {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     if (this->rdbuf()) {
       sentry __s(*this);
       if (__s) {
@@ -684,11 +687,11 @@ basic_ostream<_CharT, _Traits>& basic_ostream<_CharT, _Traits>::flush() {
           this->setstate(ios_base::badbit);
       }
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     this->__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return *this;
 }
 
@@ -797,9 +800,9 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const bitset<_Size>& __x) {
                                                          std::use_facet<ctype<_CharT> >(__os.getloc()).widen('1'));
 }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 
-#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 template <class _Traits>
 basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, wchar_t) = delete;
 
@@ -818,9 +821,9 @@ basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, co
 template <class _Traits>
 basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, const char32_t*) = delete;
 
-#  endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#    endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
-#  ifndef _LIBCPP_HAS_NO_CHAR8_T
+#    ifndef _LIBCPP_HAS_NO_CHAR8_T
 template <class _Traits>
 basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, char8_t) = delete;
 
@@ -832,7 +835,7 @@ basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const ch
 
 template <class _Traits>
 basic_ostream<wchar_t, _Traits>& operator<<(basic_ostream<wchar_t, _Traits>&, const char8_t*) = delete;
-#  endif
+#    endif
 
 template <class _Traits>
 basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, char16_t) = delete;
@@ -846,15 +849,17 @@ basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const ch
 template <class _Traits>
 basic_ostream<char, _Traits>& operator<<(basic_ostream<char, _Traits>&, const char32_t*) = delete;
 
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<char>;
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostream<wchar_t>;
-#endif
+#  endif
 
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
 #endif // _LIBCPP___OSTREAM_BASIC_OSTREAM_H
diff --git a/libcxx/include/__ostream/print.h b/libcxx/include/__ostream/print.h
index 8265ac00777e2..6c82b11e1de96 100644
--- a/libcxx/include/__ostream/print.h
+++ b/libcxx/include/__ostream/print.h
@@ -10,21 +10,24 @@
 #define _LIBCPP___OSTREAM_PRINT_H
 
 #include <__config>
-#include <__fwd/ostream.h>
-#include <__iterator/ostreambuf_iterator.h>
-#include <__ostream/basic_ostream.h>
-#include <format>
-#include <ios>
-#include <locale>
-#include <print>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
+#  include <__fwd/ostream.h>
+#  include <__iterator/ostreambuf_iterator.h>
+#  include <__ostream/basic_ostream.h>
+#  include <format>
+#  include <ios>
+#  include <locale>
+#  include <print>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 23
+#  if _LIBCPP_STD_VER >= 23
 
 template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
 _LIBCPP_HIDE_FROM_ABI inline void
@@ -49,9 +52,9 @@ __vprint_nonunicode(ostream& __os, string_view __fmt, format_args __args, bool _
     const char* __str = __o.data();
     size_t __len      = __o.size();
 
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#    endif // _LIBCPP_HAS_NO_EXCEPTIONS
       typedef ostreambuf_iterator<char> _Ip;
       if (std::__pad_and_output(
               _Ip(__os),
@@ -63,11 +66,11 @@ __vprint_nonunicode(ostream& __os, string_view __fmt, format_args __args, bool _
               .failed())
         __os.setstate(ios_base::badbit | ios_base::failbit);
 
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __os.__set_badbit_and_consider_rethrow();
     }
-#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#    endif // _LIBCPP_HAS_NO_EXCEPTIONS
   }
 }
 
@@ -91,12 +94,12 @@ _LIBCPP_HIDE_FROM_ABI inline void vprint_nonunicode(ostream& __os, string_view _
 // is determined in the same way as the print(FILE*, ...) overloads.
 _LIBCPP_EXPORTED_FROM_ABI FILE* __get_ostream_file(ostream& __os);
 
-#  ifndef _LIBCPP_HAS_NO_UNICODE
+#    ifndef _LIBCPP_HAS_NO_UNICODE
 template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
 _LIBCPP_HIDE_FROM_ABI void __vprint_unicode(ostream& __os, string_view __fmt, format_args __args, bool __write_nl) {
-#    if _LIBCPP_AVAILABILITY_HAS_PRINT == 0
+#      if _LIBCPP_AVAILABILITY_HAS_PRINT == 0
   return std::__vprint_nonunicode(__os, __fmt, __args, __write_nl);
-#    else
+#      else
   FILE* __file = std::__get_ostream_file(__os);
   if (!__file || !__print::__is_terminal(__file))
     return std::__vprint_nonunicode(__os, __fmt, __args, __write_nl);
@@ -112,49 +115,49 @@ _LIBCPP_HIDE_FROM_ABI void __vprint_unicode(ostream& __os, string_view __fmt, fo
   // This is the path for the native API, start with flushing.
   __os.flush();
 
-#      ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#        ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#      endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#        endif // _LIBCPP_HAS_NO_EXCEPTIONS
     ostream::sentry __s(__os);
     if (__s) {
-#      ifndef _LIBCPP_WIN32API
+#        ifndef _LIBCPP_WIN32API
       __print::__vprint_unicode_posix(__file, __fmt, __args, __write_nl, true);
-#      elif !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#        elif !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
     __print::__vprint_unicode_windows(__file, __fmt, __args, __write_nl, true);
-#      else
-#        error "Windows builds with wchar_t disabled are not supported."
-#      endif
+#        else
+#          error "Windows builds with wchar_t disabled are not supported."
+#        endif
     }
 
-#      ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#        ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __os.__set_badbit_and_consider_rethrow();
   }
-#      endif // _LIBCPP_HAS_NO_EXCEPTIONS
-#    endif   // _LIBCPP_AVAILABILITY_HAS_PRINT
+#        endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#      endif   // _LIBCPP_AVAILABILITY_HAS_PRINT
 }
 
 template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
 _LIBCPP_HIDE_FROM_ABI inline void vprint_unicode(ostream& __os, string_view __fmt, format_args __args) {
   std::__vprint_unicode(__os, __fmt, __args, false);
 }
-#  endif // _LIBCPP_HAS_NO_UNICODE
+#    endif // _LIBCPP_HAS_NO_UNICODE
 
 template <class... _Args>
 _LIBCPP_HIDE_FROM_ABI void print(ostream& __os, format_string<_Args...> __fmt, _Args&&... __args) {
-#  ifndef _LIBCPP_HAS_NO_UNICODE
+#    ifndef _LIBCPP_HAS_NO_UNICODE
   if constexpr (__print::__use_unicode_execution_charset)
     std::__vprint_unicode(__os, __fmt.get(), std::make_format_args(__args...), false);
   else
     std::__vprint_nonunicode(__os, __fmt.get(), std::make_format_args(__args...), false);
-#  else  // _LIBCPP_HAS_NO_UNICODE
+#    else  // _LIBCPP_HAS_NO_UNICODE
   std::__vprint_nonunicode(__os, __fmt.get(), std::make_format_args(__args...), false);
-#  endif // _LIBCPP_HAS_NO_UNICODE
+#    endif // _LIBCPP_HAS_NO_UNICODE
 }
 
 template <class... _Args>
 _LIBCPP_HIDE_FROM_ABI void println(ostream& __os, format_string<_Args...> __fmt, _Args&&... __args) {
-#  ifndef _LIBCPP_HAS_NO_UNICODE
+#    ifndef _LIBCPP_HAS_NO_UNICODE
   // Note the wording in the Standard is inefficient. The output of
   // std::format is a std::string which is then copied. This solution
   // just appends a newline at the end of the output.
@@ -162,9 +165,9 @@ _LIBCPP_HIDE_FROM_ABI void println(ostream& __os, format_string<_Args...> __fmt,
     std::__vprint_unicode(__os, __fmt.get(), std::make_format_args(__args...), true);
   else
     std::__vprint_nonunicode(__os, __fmt.get(), std::make_format_args(__args...), true);
-#  else  // _LIBCPP_HAS_NO_UNICODE
+#    else  // _LIBCPP_HAS_NO_UNICODE
   std::__vprint_nonunicode(__os, __fmt.get(), std::make_format_args(__args...), true);
-#  endif // _LIBCPP_HAS_NO_UNICODE
+#    endif // _LIBCPP_HAS_NO_UNICODE
 }
 
 template <class = void> // TODO PRINT template or availability markup fires too eagerly (http://llvm.org/PR61563).
@@ -172,8 +175,10 @@ _LIBCPP_HIDE_FROM_ABI inline void println(ostream& __os) {
   std::print(__os, "\n");
 }
 
-#endif // _LIBCPP_STD_VER >= 23
+#  endif // _LIBCPP_STD_VER >= 23
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
 #endif // _LIBCPP___OSTREAM_PRINT_H
diff --git a/libcxx/include/__thread/jthread.h b/libcxx/include/__thread/jthread.h
index d85ad3b9061b8..8fac72fff1689 100644
--- a/libcxx/include/__thread/jthread.h
+++ b/libcxx/include/__thread/jthread.h
@@ -30,7 +30,7 @@
 _LIBCPP_PUSH_MACROS
 #include <__undef_macros>
 
-#if _LIBCPP_STD_VER >= 20
+#if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_THREADS)
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -127,7 +127,7 @@ class _LIBCPP_AVAILABILITY_SYNC jthread {
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP_STD_VER >= 20
+#endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_THREADS)
 
 _LIBCPP_POP_MACROS
 
diff --git a/libcxx/include/__thread/this_thread.h b/libcxx/include/__thread/this_thread.h
index de7eea282c874..2318a9b879581 100644
--- a/libcxx/include/__thread/this_thread.h
+++ b/libcxx/include/__thread/this_thread.h
@@ -29,6 +29,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 namespace this_thread {
 
+#ifndef _LIBCPP_HAS_NO_THREADS
+
 _LIBCPP_EXPORTED_FROM_ABI void sleep_for(const chrono::nanoseconds& __ns);
 
 template <class _Rep, class _Period>
@@ -65,6 +67,8 @@ inline _LIBCPP_HIDE_FROM_ABI void sleep_until(const chrono::time_point<chrono::s
 
 inline _LIBCPP_HIDE_FROM_ABI void yield() _NOEXCEPT { __libcpp_thread_yield(); }
 
+#endif // !_LIBCPP_HAS_NO_THREADS
+
 } // namespace this_thread
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__thread/thread.h b/libcxx/include/__thread/thread.h
index 458c1cdb2da33..96de12e83b491 100644
--- a/libcxx/include/__thread/thread.h
+++ b/libcxx/include/__thread/thread.h
@@ -38,6 +38,8 @@ _LIBCPP_PUSH_MACROS
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+
 template <class _Tp>
 class __thread_specific_ptr;
 class _LIBCPP_EXPORTED_FROM_ABI __thread_struct;
@@ -118,7 +120,7 @@ struct _LIBCPP_TEMPLATE_VIS hash<__thread_id> : public __unary_function<__thread
   }
 };
 
-#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+#  ifndef _LIBCPP_HAS_NO_LOCALIZATION
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id) {
@@ -143,7 +145,7 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, __thread_id __id) {
   __sstr << __id.__id_;
   return __os << __sstr.str();
 }
-#endif // _LIBCPP_HAS_NO_LOCALIZATION
+#  endif // _LIBCPP_HAS_NO_LOCALIZATION
 
 class _LIBCPP_EXPORTED_FROM_ABI thread {
   __libcpp_thread_t __t_;
@@ -156,13 +158,13 @@ class _LIBCPP_EXPORTED_FROM_ABI thread {
   typedef __libcpp_thread_t native_handle_type;
 
   _LIBCPP_HIDE_FROM_ABI thread() _NOEXCEPT : __t_(_LIBCPP_NULL_THREAD) {}
-#ifndef _LIBCPP_CXX03_LANG
+#  ifndef _LIBCPP_CXX03_LANG
   template <class _Fp, class... _Args, __enable_if_t<!is_same<__remove_cvref_t<_Fp>, thread>::value, int> = 0>
   _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS explicit thread(_Fp&& __f, _Args&&... __args);
-#else // _LIBCPP_CXX03_LANG
+#  else // _LIBCPP_CXX03_LANG
   template <class _Fp>
   _LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS explicit thread(_Fp __f);
-#endif
+#  endif
   ~thread();
 
   _LIBCPP_HIDE_FROM_ABI thread(thread&& __t) _NOEXCEPT : __t_(__t.__t_) { __t.__t_ = _LIBCPP_NULL_THREAD; }
@@ -186,7 +188,7 @@ class _LIBCPP_EXPORTED_FROM_ABI thread {
   static unsigned hardware_concurrency() _NOEXCEPT;
 };
 
-#ifndef _LIBCPP_CXX03_LANG
+#  ifndef _LIBCPP_CXX03_LANG
 
 template <class _TSp, class _Fp, class... _Args, size_t... _Indices>
 inline _LIBCPP_HIDE_FROM_ABI void __thread_execute(tuple<_TSp, _Fp, _Args...>& __t, __tuple_indices<_Indices...>) {
@@ -216,7 +218,7 @@ thread::thread(_Fp&& __f, _Args&&... __args) {
     __throw_system_error(__ec, "thread constructor failed");
 }
 
-#else // _LIBCPP_CXX03_LANG
+#  else // _LIBCPP_CXX03_LANG
 
 template <class _Fp>
 struct __thread_invoke_pair {
@@ -248,10 +250,12 @@ thread::thread(_Fp __f) {
     __throw_system_error(__ec, "thread constructor failed");
 }
 
-#endif // _LIBCPP_CXX03_LANG
+#  endif // _LIBCPP_CXX03_LANG
 
 inline _LIBCPP_HIDE_FROM_ABI void swap(thread& __x, thread& __y) _NOEXCEPT { __x.swap(__y); }
 
+#endif // !defined(_LIBCPP_HAS_NO_THREADS)
+
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
diff --git a/libcxx/include/fstream b/libcxx/include/fstream
index a77b7ce06f2aa..1cc3bd8858e12 100644
--- a/libcxx/include/fstream
+++ b/libcxx/include/fstream
@@ -215,7 +215,7 @@ _LIBCPP_PUSH_MACROS
 #  define _LIBCPP_HAS_NO_OFF_T_FUNCTIONS
 #endif
 
-#if !defined(_LIBCPP_HAS_NO_FILESYSTEM)
+#if !defined(_LIBCPP_HAS_NO_FILESYSTEM) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -1560,7 +1560,7 @@ extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_filebuf<char>;
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP_HAS_NO_FILESYSTEM
+#endif // !defined(_LIBCPP_HAS_NO_FILESYSTEM) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 
 _LIBCPP_POP_MACROS
 
diff --git a/libcxx/include/iomanip b/libcxx/include/iomanip
index fb4f15b9a5853..70c8c354e86f2 100644
--- a/libcxx/include/iomanip
+++ b/libcxx/include/iomanip
@@ -43,12 +43,15 @@ template <class charT, class traits, class Allocator>
 */
 
 #include <__config>
-#include <istream>
-#include <version>
 
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+
+#  include <istream>
+#  include <version>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -231,9 +234,9 @@ public:
 template <class _CharT, class _Traits, class _MoneyT>
 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 operator>>(basic_istream<_CharT, _Traits>& __is, const __iom_t7<_MoneyT>& __x) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     typename basic_istream<_CharT, _Traits>::sentry __s(__is);
     if (__s) {
       typedef istreambuf_iterator<_CharT, _Traits> _Ip;
@@ -243,11 +246,11 @@ operator>>(basic_istream<_CharT, _Traits>& __is, const __iom_t7<_MoneyT>& __x) {
       __mf.get(_Ip(__is), _Ip(), __x.__intl_, __is, __err, __x.__mon_);
       __is.setstate(__err);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __is.__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return __is;
 }
 
@@ -280,9 +283,9 @@ public:
 template <class _CharT, class _Traits, class _MoneyT>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, const __iom_t8<_MoneyT>& __x) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     typename basic_ostream<_CharT, _Traits>::sentry __s(__os);
     if (__s) {
       typedef ostreambuf_iterator<_CharT, _Traits> _Op;
@@ -291,11 +294,11 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const __iom_t8<_MoneyT>& __x) {
       if (__mf.put(_Op(__os), __x.__intl_, __os, __os.fill(), __x.__mon_).failed())
         __os.setstate(ios_base::badbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __os.__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return __os;
 }
 
@@ -328,9 +331,9 @@ public:
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
 operator>>(basic_istream<_CharT, _Traits>& __is, const __iom_t9<_CharT>& __x) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     typename basic_istream<_CharT, _Traits>::sentry __s(__is);
     if (__s) {
       typedef istreambuf_iterator<_CharT, _Traits> _Ip;
@@ -340,11 +343,11 @@ operator>>(basic_istream<_CharT, _Traits>& __is, const __iom_t9<_CharT>& __x) {
       __tf.get(_Ip(__is), _Ip(), __is, __err, __x.__tm_, __x.__fmt_, __x.__fmt_ + _Traits::length(__x.__fmt_));
       __is.setstate(__err);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __is.__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return __is;
 }
 
@@ -377,9 +380,9 @@ public:
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, const __iom_t10<_CharT>& __x) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     typename basic_ostream<_CharT, _Traits>::sentry __s(__os);
     if (__s) {
       typedef ostreambuf_iterator<_CharT, _Traits> _Op;
@@ -389,11 +392,11 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, const __iom_t10<_CharT>& __x) {
               .failed())
         __os.setstate(ios_base::badbit);
     }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
   } catch (...) {
     __os.__set_badbit_and_consider_rethrow();
   }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   return __os;
 }
 
@@ -505,7 +508,7 @@ __quoted(basic_string<_CharT, _Traits, _Allocator>& __s, _CharT __delim = _CharT
   return __quoted_proxy<_CharT, _Traits, _Allocator>(__s, __delim, __escape);
 }
 
-#if _LIBCPP_STD_VER >= 14
+#  if _LIBCPP_STD_VER >= 14
 
 template <class _CharT>
 _LIBCPP_HIDE_FROM_ABI auto quoted(const _CharT* __s, _CharT __delim = _CharT('"'), _CharT __escape = _CharT('\\')) {
@@ -535,8 +538,10 @@ quoted(basic_string_view<_CharT, _Traits> __sv, _CharT __delim = _CharT('"'), _C
   return __quoted_output_proxy<_CharT, _Traits>(__sv.data(), __sv.data() + __sv.size(), __delim, __escape);
 }
 
-#endif // _LIBCPP_STD_VER >= 14
+#  endif // _LIBCPP_STD_VER >= 14
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !_LIBCPP_HAS_NO_LOCALIZATION
+
 #endif // _LIBCPP_IOMANIP
diff --git a/libcxx/include/istream b/libcxx/include/istream
index 7c65a24bc313d..8ee29ba3302f2 100644
--- a/libcxx/include/istream
+++ b/libcxx/include/istream
@@ -159,26 +159,29 @@ template <class Stream, class T>
 */
 
 #include <__config>
-#include <__fwd/istream.h>
-#include <__iterator/istreambuf_iterator.h>
-#include <__ostream/basic_ostream.h>
-#include <__type_traits/conjunction.h>
-#include <__type_traits/enable_if.h>
-#include <__type_traits/is_base_of.h>
-#include <__type_traits/make_unsigned.h>
-#include <__utility/declval.h>
-#include <__utility/forward.h>
-#include <bitset>
-#include <ios>
-#include <locale>
-#include <version>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
+#  include <__fwd/istream.h>
+#  include <__iterator/istreambuf_iterator.h>
+#  include <__ostream/basic_ostream.h>
+#  include <__type_traits/conjunction.h>
+#  include <__type_traits/enable_if.h>
+#  include <__type_traits/is_base_of.h>
+#  include <__type_traits/make_unsigned.h>
+#  include <__utility/declval.h>
+#  include <__utility/forward.h>
+#  include <bitset>
+#  include <ios>
+#  include <locale>
+#  include <version>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_PUSH_MACROS
-#include <__undef_macros>
+#  include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -354,13 +357,13 @@ __input_arithmetic(basic_istream<_CharT, _Traits>& __is, _Tp& __n) {
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __s(__is);
   if (__s) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       typedef istreambuf_iterator<_CharT, _Traits> _Ip;
       typedef num_get<_CharT, _Ip> _Fp;
       std::use_facet<_Fp>(__is.getloc()).get(_Ip(__is), _Ip(), __is, __state, __n);
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -368,7 +371,7 @@ __input_arithmetic(basic_istream<_CharT, _Traits>& __is, _Tp& __n) {
         throw;
       }
     }
-#endif
+#  endif
     __is.setstate(__state);
   }
   return __is;
@@ -435,9 +438,9 @@ __input_arithmetic_with_numeric_limits(basic_istream<_CharT, _Traits>& __is, _Tp
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __s(__is);
   if (__s) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       typedef istreambuf_iterator<_CharT, _Traits> _Ip;
       typedef num_get<_CharT, _Ip> _Fp;
       long __temp;
@@ -451,7 +454,7 @@ __input_arithmetic_with_numeric_limits(basic_istream<_CharT, _Traits>& __is, _Tp
       } else {
         __n = static_cast<_Tp>(__temp);
       }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -459,7 +462,7 @@ __input_arithmetic_with_numeric_limits(basic_istream<_CharT, _Traits>& __is, _Tp
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     __is.setstate(__state);
   }
   return __is;
@@ -481,9 +484,9 @@ __input_c_string(basic_istream<_CharT, _Traits>& __is, _CharT* __p, size_t __n)
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __sen(__is);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif
+#  endif
       _CharT* __s               = __p;
       const ctype<_CharT>& __ct = std::use_facet<ctype<_CharT> >(__is.getloc());
       while (__s != __p + (__n - 1)) {
@@ -502,7 +505,7 @@ __input_c_string(basic_istream<_CharT, _Traits>& __is, _CharT* __p, size_t __n)
       __is.width(0);
       if (__s == __p)
         __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -510,13 +513,13 @@ __input_c_string(basic_istream<_CharT, _Traits>& __is, _CharT* __p, size_t __n)
         throw;
       }
     }
-#endif
+#  endif
     __is.setstate(__state);
   }
   return __is;
 }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 
 template <class _CharT, class _Traits, size_t _Np>
 inline _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
@@ -539,7 +542,7 @@ operator>>(basic_istream<char, _Traits>& __is, signed char (&__buf)[_Np]) {
   return __is >> (char(&)[_Np])__buf;
 }
 
-#else
+#  else
 
 template <class _CharT, class _Traits>
 inline _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>&
@@ -562,22 +565,22 @@ operator>>(basic_istream<char, _Traits>& __is, signed char* __s) {
   return __is >> (char*)__s;
 }
 
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
 template <class _CharT, class _Traits>
 _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& operator>>(basic_istream<_CharT, _Traits>& __is, _CharT& __c) {
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __sen(__is);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif
+#  endif
       typename _Traits::int_type __i = __is.rdbuf()->sbumpc();
       if (_Traits::eq_int_type(__i, _Traits::eof()))
         __state |= ios_base::eofbit | ios_base::failbit;
       else
         __c = _Traits::to_char_type(__i);
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -585,7 +588,7 @@ _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& operator>>(basic_istream<_
         throw;
       }
     }
-#endif
+#  endif
     __is.setstate(__state);
   }
   return __is;
@@ -611,9 +614,9 @@ basic_istream<_CharT, _Traits>::operator>>(basic_streambuf<char_type, traits_typ
   sentry __s(*this, true);
   if (__s) {
     if (__sb) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
         while (true) {
           typename traits_type::int_type __i = this->rdbuf()->sgetc();
           if (traits_type::eq_int_type(__i, _Traits::eof())) {
@@ -627,7 +630,7 @@ basic_istream<_CharT, _Traits>::operator>>(basic_streambuf<char_type, traits_typ
         }
         if (__gc_ == 0)
           __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       } catch (...) {
         __state |= ios_base::badbit;
         if (__gc_ == 0)
@@ -638,7 +641,7 @@ basic_istream<_CharT, _Traits>::operator>>(basic_streambuf<char_type, traits_typ
           throw;
         }
       }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     } else {
       __state |= ios_base::failbit;
     }
@@ -654,22 +657,22 @@ typename basic_istream<_CharT, _Traits>::int_type basic_istream<_CharT, _Traits>
   int_type __r              = traits_type::eof();
   sentry __s(*this, true);
   if (__s) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif
+#  endif
       __r = this->rdbuf()->sbumpc();
       if (traits_type::eq_int_type(__r, traits_type::eof()))
         __state |= ios_base::failbit | ios_base::eofbit;
       else
         __gc_ = 1;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       this->__setstate_nothrow(this->rdstate() | ios_base::badbit);
       if (this->exceptions() & ios_base::badbit) {
         throw;
       }
     }
-#endif
+#  endif
     this->setstate(__state);
   }
   return __r;
@@ -682,9 +685,9 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::get(char_type* _
   sentry __sen(*this, true);
   if (__sen) {
     if (__n > 0) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       try {
-#endif
+#  endif
         while (__gc_ < __n - 1) {
           int_type __i = this->rdbuf()->sgetc();
           if (traits_type::eq_int_type(__i, traits_type::eof())) {
@@ -700,7 +703,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::get(char_type* _
         }
         if (__gc_ == 0)
           __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       } catch (...) {
         __state |= ios_base::badbit;
         this->__setstate_nothrow(__state);
@@ -710,7 +713,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::get(char_type* _
           throw;
         }
       }
-#endif
+#  endif
     } else {
       __state |= ios_base::failbit;
     }
@@ -731,9 +734,9 @@ basic_istream<_CharT, _Traits>::get(basic_streambuf<char_type, traits_type>& __s
   __gc_                     = 0;
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       while (true) {
         typename traits_type::int_type __i = this->rdbuf()->sgetc();
         if (traits_type::eq_int_type(__i, traits_type::eof())) {
@@ -748,12 +751,12 @@ basic_istream<_CharT, _Traits>::get(basic_streambuf<char_type, traits_type>& __s
         __inc_gcount();
         this->rdbuf()->sbumpc();
       }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       // according to the spec, exceptions here are caught but not rethrown
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     if (__gc_ == 0)
       __state |= ios_base::failbit;
     this->setstate(__state);
@@ -768,9 +771,9 @@ basic_istream<_CharT, _Traits>::getline(char_type* __s, streamsize __n, char_typ
   __gc_                     = 0;
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       while (true) {
         typename traits_type::int_type __i = this->rdbuf()->sgetc();
         if (traits_type::eq_int_type(__i, traits_type::eof())) {
@@ -791,7 +794,7 @@ basic_istream<_CharT, _Traits>::getline(char_type* __s, streamsize __n, char_typ
         this->rdbuf()->sbumpc();
         __inc_gcount();
       }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -803,7 +806,7 @@ basic_istream<_CharT, _Traits>::getline(char_type* __s, streamsize __n, char_typ
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   }
   if (__n > 0)
     *__s = char_type();
@@ -819,9 +822,9 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::ignore(streamsiz
   __gc_                     = 0;
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       if (__n == numeric_limits<streamsize>::max()) {
         while (true) {
           typename traits_type::int_type __i = this->rdbuf()->sbumpc();
@@ -845,7 +848,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::ignore(streamsiz
             break;
         }
       }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -853,7 +856,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::ignore(streamsiz
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     this->setstate(__state);
   }
   return *this;
@@ -866,13 +869,13 @@ typename basic_istream<_CharT, _Traits>::int_type basic_istream<_CharT, _Traits>
   int_type __r              = traits_type::eof();
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       __r = this->rdbuf()->sgetc();
       if (traits_type::eq_int_type(__r, traits_type::eof()))
         __state |= ios_base::eofbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -880,7 +883,7 @@ typename basic_istream<_CharT, _Traits>::int_type basic_istream<_CharT, _Traits>
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     this->setstate(__state);
   }
   return __r;
@@ -892,13 +895,13 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::read(char_type*
   __gc_                     = 0;
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       __gc_ = this->rdbuf()->sgetn(__s, __n);
       if (__gc_ != __n)
         __state |= ios_base::failbit | ios_base::eofbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -906,7 +909,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::read(char_type*
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   } else {
     __state |= ios_base::failbit;
   }
@@ -920,9 +923,9 @@ streamsize basic_istream<_CharT, _Traits>::readsome(char_type* __s, streamsize _
   __gc_                     = 0;
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       streamsize __c = this->rdbuf()->in_avail();
       switch (__c) {
       case -1:
@@ -937,7 +940,7 @@ streamsize basic_istream<_CharT, _Traits>::readsome(char_type* __s, streamsize _
           __state |= ios_base::failbit | ios_base::eofbit;
         break;
       }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -945,7 +948,7 @@ streamsize basic_istream<_CharT, _Traits>::readsome(char_type* __s, streamsize _
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   } else {
     __state |= ios_base::failbit;
   }
@@ -960,12 +963,12 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::putback(char_typ
   this->clear(__state);
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       if (this->rdbuf() == nullptr || this->rdbuf()->sputbackc(__c) == traits_type::eof())
         __state |= ios_base::badbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -973,7 +976,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::putback(char_typ
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   } else {
     __state |= ios_base::failbit;
   }
@@ -988,12 +991,12 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::unget() {
   this->clear(__state);
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       if (this->rdbuf() == nullptr || this->rdbuf()->sungetc() == traits_type::eof())
         __state |= ios_base::badbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -1001,7 +1004,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::unget() {
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
   } else {
     __state |= ios_base::failbit;
   }
@@ -1018,14 +1021,14 @@ int basic_istream<_CharT, _Traits>::sync() {
 
   int __r = 0;
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       if (this->rdbuf()->pubsync() == -1) {
         __state |= ios_base::badbit;
         __r = -1;
       }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -1033,7 +1036,7 @@ int basic_istream<_CharT, _Traits>::sync() {
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     this->setstate(__state);
   }
   return __r;
@@ -1045,11 +1048,11 @@ typename basic_istream<_CharT, _Traits>::pos_type basic_istream<_CharT, _Traits>
   pos_type __r(-1);
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       __r = this->rdbuf()->pubseekoff(0, ios_base::cur, ios_base::in);
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -1057,7 +1060,7 @@ typename basic_istream<_CharT, _Traits>::pos_type basic_istream<_CharT, _Traits>
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     this->setstate(__state);
   }
   return __r;
@@ -1069,12 +1072,12 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::seekg(pos_type _
   this->clear(__state);
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       if (this->rdbuf()->pubseekpos(__pos, ios_base::in) == pos_type(-1))
         __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -1082,7 +1085,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::seekg(pos_type _
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     this->setstate(__state);
   }
   return *this;
@@ -1094,12 +1097,12 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::seekg(off_type _
   this->clear(__state);
   sentry __sen(*this, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       if (this->rdbuf()->pubseekoff(__off, __dir, ios_base::in) == pos_type(-1))
         __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       this->__setstate_nothrow(__state);
@@ -1107,7 +1110,7 @@ basic_istream<_CharT, _Traits>& basic_istream<_CharT, _Traits>::seekg(off_type _
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     this->setstate(__state);
   }
   return *this;
@@ -1118,9 +1121,9 @@ _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& ws(basic_istream<_CharT, _
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __sen(__is, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
       const ctype<_CharT>& __ct = std::use_facet<ctype<_CharT> >(__is.getloc());
       while (true) {
         typename _Traits::int_type __i = __is.rdbuf()->sgetc();
@@ -1132,7 +1135,7 @@ _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& ws(basic_istream<_CharT, _
           break;
         __is.rdbuf()->sbumpc();
       }
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -1140,7 +1143,7 @@ _LIBCPP_HIDE_FROM_ABI basic_istream<_CharT, _Traits>& ws(basic_istream<_CharT, _
         throw;
       }
     }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     __is.setstate(__state);
   }
   return __is;
@@ -1208,9 +1211,9 @@ operator>>(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __sen(__is);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif
+#  endif
       __str.clear();
       using _Size              = typename basic_string<_CharT, _Traits, _Allocator>::size_type;
       streamsize const __width = __is.width();
@@ -1240,7 +1243,7 @@ operator>>(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _
       __is.width(0);
       if (__c == 0)
         __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -1248,7 +1251,7 @@ operator>>(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _
         throw;
       }
     }
-#endif
+#  endif
     __is.setstate(__state);
   }
   return __is;
@@ -1260,9 +1263,9 @@ getline(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _All
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __sen(__is, true);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif
+#  endif
       __str.clear();
       streamsize __extr = 0;
       while (true) {
@@ -1283,7 +1286,7 @@ getline(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _All
       }
       if (__extr == 0)
         __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -1291,7 +1294,7 @@ getline(basic_istream<_CharT, _Traits>& __is, basic_string<_CharT, _Traits, _All
         throw;
       }
     }
-#endif
+#  endif
     __is.setstate(__state);
   }
   return __is;
@@ -1321,9 +1324,9 @@ operator>>(basic_istream<_CharT, _Traits>& __is, bitset<_Size>& __x) {
   ios_base::iostate __state = ios_base::goodbit;
   typename basic_istream<_CharT, _Traits>::sentry __sen(__is);
   if (__sen) {
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#endif
+#  endif
       basic_string<_CharT, _Traits> __str;
       const ctype<_CharT>& __ct = std::use_facet<ctype<_CharT> >(__is.getloc());
       size_t __c                = 0;
@@ -1345,7 +1348,7 @@ operator>>(basic_istream<_CharT, _Traits>& __is, bitset<_Size>& __x) {
       __x = bitset<_Size>(__str);
       if (_Size > 0 && __c == 0)
         __state |= ios_base::failbit;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
       __state |= ios_base::badbit;
       __is.__setstate_nothrow(__state);
@@ -1353,20 +1356,22 @@ operator>>(basic_istream<_CharT, _Traits>& __is, bitset<_Size>& __x) {
         throw;
       }
     }
-#endif
+#  endif
     __is.setstate(__state);
   }
   return __is;
 }
 
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_istream<char>;
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_istream<wchar_t>;
-#endif
+#  endif
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_iostream<char>;
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #  include <concepts>
 #  include <iosfwd>
diff --git a/libcxx/include/ostream b/libcxx/include/ostream
index 359d3c0e19c4c..83742882f7bb6 100644
--- a/libcxx/include/ostream
+++ b/libcxx/include/ostream
@@ -174,17 +174,21 @@ void vprint_nonunicode(ostream& os, string_view fmt, format_args args);
 
 #include <__config>
 
-#include <__ostream/basic_ostream.h>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 
-#if _LIBCPP_STD_VER >= 23
-#  include <__ostream/print.h>
-#endif
+#  include <__ostream/basic_ostream.h>
 
-#include <version>
+#  if _LIBCPP_STD_VER >= 23
+#    include <__ostream/print.h>
+#  endif
 
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+#  include <version>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
+
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
 
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #  include <atomic>
diff --git a/libcxx/include/sstream b/libcxx/include/sstream
index 78a7f2d5901d2..553cc08b122cf 100644
--- a/libcxx/include/sstream
+++ b/libcxx/include/sstream
@@ -313,21 +313,24 @@ typedef basic_stringstream<wchar_t> wstringstream;
 // clang-format on
 
 #include <__config>
-#include <__fwd/sstream.h>
-#include <__ostream/basic_ostream.h>
-#include <__type_traits/is_convertible.h>
-#include <__utility/swap.h>
-#include <istream>
-#include <string>
-#include <string_view>
-#include <version>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+
+#ifndef _LIBCPP_HAS_NO_LOCALIZATION
+
+#  include <__fwd/sstream.h>
+#  include <__ostream/basic_ostream.h>
+#  include <__type_traits/is_convertible.h>
+#  include <__utility/swap.h>
+#  include <istream>
+#  include <string>
+#  include <string_view>
+#  include <version>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_PUSH_MACROS
-#include <__undef_macros>
+#  include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -370,7 +373,7 @@ public:
     str(__s);
   }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI explicit basic_stringbuf(const allocator_type& __a)
       : basic_stringbuf(ios_base::in | ios_base::out, __a) {}
 
@@ -404,9 +407,9 @@ public:
       : __str_(__s), __hm_(nullptr), __mode_(__wch) {
     __init_buf_ptrs();
   }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
 
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
@@ -428,37 +431,37 @@ public:
     __init_buf_ptrs();
   }
 
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 
   basic_stringbuf(const basic_stringbuf&) = delete;
   basic_stringbuf(basic_stringbuf&& __rhs) : __mode_(__rhs.__mode_) { __move_init(std::move(__rhs)); }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI basic_stringbuf(basic_stringbuf&& __rhs, const allocator_type& __a)
       : basic_stringbuf(__rhs.__mode_, __a) {
     __move_init(std::move(__rhs));
   }
-#endif
+#  endif
 
   // [stringbuf.assign] Assign and swap:
   basic_stringbuf& operator=(const basic_stringbuf&) = delete;
   basic_stringbuf& operator=(basic_stringbuf&& __rhs);
   void swap(basic_stringbuf& __rhs)
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
       noexcept(allocator_traits<allocator_type>::propagate_on_container_swap::value ||
                allocator_traits<allocator_type>::is_always_equal::value)
-#endif
+#  endif
           ;
 
   // [stringbuf.members] Member functions:
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI allocator_type get_allocator() const noexcept { return __str_.get_allocator(); }
-#endif
+#  endif
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
+#  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
   string_type str() const;
-#else
+#  else
   _LIBCPP_HIDE_FROM_ABI string_type str() const& { return str(__str_.get_allocator()); }
 
   _LIBCPP_HIDE_FROM_ABI string_type str() && {
@@ -472,9 +475,9 @@ public:
     __init_buf_ptrs();
     return __result;
   }
-#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
+#  endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
     requires __is_allocator<_SAlloc>::value
   _LIBCPP_HIDE_FROM_ABI basic_string<char_type, traits_type, _SAlloc> str(const _SAlloc& __sa) const {
@@ -482,14 +485,14 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI basic_string_view<char_type, traits_type> view() const noexcept;
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
   void str(const string_type& __s) {
     __str_ = __s;
     __init_buf_ptrs();
   }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
     requires(!is_same_v<_SAlloc, allocator_type>)
   _LIBCPP_HIDE_FROM_ABI void str(const basic_string<char_type, traits_type, _SAlloc>& __s) {
@@ -501,9 +504,9 @@ public:
     __str_ = std::move(__s);
     __init_buf_ptrs();
   }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
 
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
@@ -513,7 +516,7 @@ public:
     __init_buf_ptrs();
   }
 
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 
 protected:
   // [stringbuf.virtuals] Overridden virtual functions:
@@ -609,10 +612,10 @@ basic_stringbuf<_CharT, _Traits, _Allocator>::operator=(basic_stringbuf&& __rhs)
 
 template <class _CharT, class _Traits, class _Allocator>
 void basic_stringbuf<_CharT, _Traits, _Allocator>::swap(basic_stringbuf& __rhs)
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
     noexcept(allocator_traits<_Allocator>::propagate_on_container_swap::value ||
              allocator_traits<_Allocator>::is_always_equal::value)
-#endif
+#  endif
 {
   char_type* __p    = const_cast<char_type*>(__rhs.__str_.data());
   ptrdiff_t __rbinp = -1;
@@ -682,14 +685,14 @@ void basic_stringbuf<_CharT, _Traits, _Allocator>::swap(basic_stringbuf& __rhs)
 template <class _CharT, class _Traits, class _Allocator>
 inline _LIBCPP_HIDE_FROM_ABI void
 swap(basic_stringbuf<_CharT, _Traits, _Allocator>& __x, basic_stringbuf<_CharT, _Traits, _Allocator>& __y)
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
     noexcept(noexcept(__x.swap(__y)))
-#endif
+#  endif
 {
   __x.swap(__y);
 }
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
+#  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
 template <class _CharT, class _Traits, class _Allocator>
 basic_string<_CharT, _Traits, _Allocator> basic_stringbuf<_CharT, _Traits, _Allocator>::str() const {
   if (__mode_ & ios_base::out) {
@@ -700,7 +703,7 @@ basic_string<_CharT, _Traits, _Allocator> basic_stringbuf<_CharT, _Traits, _Allo
     return string_type(this->eback(), this->egptr(), __str_.get_allocator());
   return string_type(__str_.get_allocator());
 }
-#endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
+#  endif // _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
 
 template <class _CharT, class _Traits, class _Allocator>
 _LIBCPP_HIDE_FROM_ABI void basic_stringbuf<_CharT, _Traits, _Allocator>::__init_buf_ptrs() {
@@ -726,7 +729,7 @@ _LIBCPP_HIDE_FROM_ABI void basic_stringbuf<_CharT, _Traits, _Allocator>::__init_
   }
 }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
 template <class _CharT, class _Traits, class _Allocator>
 _LIBCPP_HIDE_FROM_ABI basic_string_view<_CharT, _Traits>
 basic_stringbuf<_CharT, _Traits, _Allocator>::view() const noexcept {
@@ -738,7 +741,7 @@ basic_stringbuf<_CharT, _Traits, _Allocator>::view() const noexcept {
     return basic_string_view<_CharT, _Traits>(this->eback(), this->egptr());
   return basic_string_view<_CharT, _Traits>();
 }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
 template <class _CharT, class _Traits, class _Allocator>
 typename basic_stringbuf<_CharT, _Traits, _Allocator>::int_type
@@ -781,9 +784,9 @@ basic_stringbuf<_CharT, _Traits, _Allocator>::overflow(int_type __c) {
     if (this->pptr() == this->epptr()) {
       if (!(__mode_ & ios_base::out))
         return traits_type::eof();
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       try {
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
         ptrdiff_t __nout = this->pptr() - this->pbase();
         ptrdiff_t __hm   = __hm_ - this->pbase();
         __str_.push_back(char_type());
@@ -792,11 +795,11 @@ basic_stringbuf<_CharT, _Traits, _Allocator>::overflow(int_type __c) {
         this->setp(__p, __p + __str_.size());
         this->__pbump(__nout);
         __hm_ = this->pbase() + __hm;
-#ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       } catch (...) {
         return traits_type::eof();
       }
-#endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
     }
     __hm_ = std::max(this->pptr() + 1, __hm_);
     if (__mode_ & ios_base::in) {
@@ -881,7 +884,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI explicit basic_istringstream(const string_type& __s, ios_base::openmode __wch = ios_base::in)
       : basic_istream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::in) {}
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI basic_istringstream(ios_base::openmode __wch, const _Allocator& __a)
       : basic_istream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__wch | ios_base::in, __a) {}
 
@@ -901,9 +904,9 @@ public:
   _LIBCPP_HIDE_FROM_ABI explicit basic_istringstream(const basic_string<_CharT, _Traits, _SAlloc>& __s,
                                                      ios_base::openmode __wch = ios_base::in)
       : basic_istream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::in) {}
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
 
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
@@ -920,7 +923,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI basic_istringstream(const _Tp& __t, ios_base::openmode __which, const _Allocator& __a)
       : basic_istream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__t, __which | ios_base::in, __a) {}
 
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 
   basic_istringstream(const basic_istringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_istringstream(basic_istringstream&& __rhs)
@@ -945,15 +948,15 @@ public:
     return const_cast<basic_stringbuf<char_type, traits_type, allocator_type>*>(std::addressof(__sb_));
   }
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
+#  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
   _LIBCPP_HIDE_FROM_ABI string_type str() const { return __sb_.str(); }
-#else
+#  else
   _LIBCPP_HIDE_FROM_ABI string_type str() const& { return __sb_.str(); }
 
   _LIBCPP_HIDE_FROM_ABI string_type str() && { return std::move(__sb_).str(); }
-#endif
+#  endif
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
     requires __is_allocator<_SAlloc>::value
   _LIBCPP_HIDE_FROM_ABI basic_string<char_type, traits_type, _SAlloc> str(const _SAlloc& __sa) const {
@@ -961,26 +964,26 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI basic_string_view<char_type, traits_type> view() const noexcept { return __sb_.view(); }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
   _LIBCPP_HIDE_FROM_ABI void str(const string_type& __s) { __sb_.str(__s); }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
   _LIBCPP_HIDE_FROM_ABI void str(const basic_string<char_type, traits_type, _SAlloc>& __s) {
     __sb_.str(__s);
   }
 
   _LIBCPP_HIDE_FROM_ABI void str(string_type&& __s) { __sb_.str(std::move(__s)); }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
   _LIBCPP_HIDE_FROM_ABI void str(const _Tp& __t) {
     rdbuf()->str(__t);
   }
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 };
 
 template <class _CharT, class _Traits, class _Allocator>
@@ -1017,7 +1020,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI explicit basic_ostringstream(const string_type& __s, ios_base::openmode __wch = ios_base::out)
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::out) {}
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI basic_ostringstream(ios_base::openmode __wch, const _Allocator& __a)
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__wch | ios_base::out, __a) {}
 
@@ -1038,9 +1041,9 @@ public:
   _LIBCPP_HIDE_FROM_ABI explicit basic_ostringstream(const basic_string<_CharT, _Traits, _SAlloc>& __s,
                                                      ios_base::openmode __wch = ios_base::out)
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch | ios_base::out) {}
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
 
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
@@ -1057,7 +1060,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI basic_ostringstream(const _Tp& __t, ios_base::openmode __which, const _Allocator& __a)
       : basic_ostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__t, __which | ios_base::out, __a) {}
 
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 
   basic_ostringstream(const basic_ostringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_ostringstream(basic_ostringstream&& __rhs)
@@ -1083,15 +1086,15 @@ public:
     return const_cast<basic_stringbuf<char_type, traits_type, allocator_type>*>(std::addressof(__sb_));
   }
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
+#  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
   _LIBCPP_HIDE_FROM_ABI string_type str() const { return __sb_.str(); }
-#else
+#  else
   _LIBCPP_HIDE_FROM_ABI string_type str() const& { return __sb_.str(); }
 
   _LIBCPP_HIDE_FROM_ABI string_type str() && { return std::move(__sb_).str(); }
-#endif
+#  endif
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
     requires __is_allocator<_SAlloc>::value
   _LIBCPP_HIDE_FROM_ABI basic_string<char_type, traits_type, _SAlloc> str(const _SAlloc& __sa) const {
@@ -1099,26 +1102,26 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI basic_string_view<char_type, traits_type> view() const noexcept { return __sb_.view(); }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
   _LIBCPP_HIDE_FROM_ABI void str(const string_type& __s) { __sb_.str(__s); }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
   _LIBCPP_HIDE_FROM_ABI void str(const basic_string<char_type, traits_type, _SAlloc>& __s) {
     __sb_.str(__s);
   }
 
   _LIBCPP_HIDE_FROM_ABI void str(string_type&& __s) { __sb_.str(std::move(__s)); }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
   _LIBCPP_HIDE_FROM_ABI void str(const _Tp& __t) {
     rdbuf()->str(__t);
   }
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 };
 
 template <class _CharT, class _Traits, class _Allocator>
@@ -1156,7 +1159,7 @@ public:
                                                     ios_base::openmode __wch = ios_base::in | ios_base::out)
       : basic_iostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch) {}
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI basic_stringstream(ios_base::openmode __wch, const _Allocator& __a)
       : basic_iostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__wch, __a) {}
 
@@ -1178,9 +1181,9 @@ public:
   _LIBCPP_HIDE_FROM_ABI explicit basic_stringstream(const basic_string<_CharT, _Traits, _SAlloc>& __s,
                                                     ios_base::openmode __wch = ios_base::out | ios_base::in)
       : basic_iostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__s, __wch) {}
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
 
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
@@ -1198,7 +1201,7 @@ public:
   _LIBCPP_HIDE_FROM_ABI basic_stringstream(const _Tp& __t, ios_base::openmode __which, const _Allocator& __a)
       : basic_iostream<_CharT, _Traits>(std::addressof(__sb_)), __sb_(__t, __which, __a) {}
 
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 
   basic_stringstream(const basic_stringstream&) = delete;
   _LIBCPP_HIDE_FROM_ABI basic_stringstream(basic_stringstream&& __rhs)
@@ -1223,15 +1226,15 @@ public:
     return const_cast<basic_stringbuf<char_type, traits_type, allocator_type>*>(std::addressof(__sb_));
   }
 
-#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
+#  if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_BUILDING_LIBRARY)
   _LIBCPP_HIDE_FROM_ABI string_type str() const { return __sb_.str(); }
-#else
+#  else
   _LIBCPP_HIDE_FROM_ABI string_type str() const& { return __sb_.str(); }
 
   _LIBCPP_HIDE_FROM_ABI string_type str() && { return std::move(__sb_).str(); }
-#endif
+#  endif
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
     requires __is_allocator<_SAlloc>::value
   _LIBCPP_HIDE_FROM_ABI basic_string<char_type, traits_type, _SAlloc> str(const _SAlloc& __sa) const {
@@ -1239,26 +1242,26 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI basic_string_view<char_type, traits_type> view() const noexcept { return __sb_.view(); }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
   _LIBCPP_HIDE_FROM_ABI void str(const string_type& __s) { __sb_.str(__s); }
 
-#if _LIBCPP_STD_VER >= 20
+#  if _LIBCPP_STD_VER >= 20
   template <class _SAlloc>
   _LIBCPP_HIDE_FROM_ABI void str(const basic_string<char_type, traits_type, _SAlloc>& __s) {
     __sb_.str(__s);
   }
 
   _LIBCPP_HIDE_FROM_ABI void str(string_type&& __s) { __sb_.str(std::move(__s)); }
-#endif // _LIBCPP_STD_VER >= 20
+#  endif // _LIBCPP_STD_VER >= 20
 
-#if _LIBCPP_STD_VER >= 26
+#  if _LIBCPP_STD_VER >= 26
   template <class _Tp>
     requires is_convertible_v<const _Tp&, basic_string_view<_CharT, _Traits>>
   _LIBCPP_HIDE_FROM_ABI void str(const _Tp& __t) {
     rdbuf()->str(__t);
   }
-#endif //  _LIBCPP_STD_VER >= 26
+#  endif //  _LIBCPP_STD_VER >= 26
 };
 
 template <class _CharT, class _Traits, class _Allocator>
@@ -1267,17 +1270,19 @@ swap(basic_stringstream<_CharT, _Traits, _Allocator>& __x, basic_stringstream<_C
   __x.swap(__y);
 }
 
-#if _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1
+#  if _LIBCPP_AVAILABILITY_HAS_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_stringbuf<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_stringstream<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostringstream<char>;
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_istringstream<char>;
-#endif
+#  endif
 
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
+#endif // !_LIBCPP_HAS_NO_LOCALIZATION
+
 #if _LIBCPP_STD_VER <= 20 && !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES)
 #  include <ostream>
 #  include <type_traits>
diff --git a/libcxx/include/streambuf b/libcxx/include/streambuf
index 5a3c17ef7c99e..906340ef03335 100644
--- a/libcxx/include/streambuf
+++ b/libcxx/include/streambuf
@@ -107,23 +107,26 @@ protected:
 
 */
 
-#include <__assert>
 #include <__config>
-#include <__fwd/streambuf.h>
-#include <__locale>
-#include <__type_traits/is_same.h>
-#include <__utility/is_valid_range.h>
-#include <climits>
-#include <ios>
-#include <iosfwd>
-#include <version>
-
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
+#  include <__assert>
+#  include <__fwd/streambuf.h>
+#  include <__locale>
+#  include <__type_traits/is_same.h>
+#  include <__utility/is_valid_range.h>
+#  include <climits>
+#  include <ios>
+#  include <iosfwd>
+#  include <version>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_PUSH_MACROS
-#include <__undef_macros>
+#  include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -430,14 +433,16 @@ typename basic_streambuf<_CharT, _Traits>::int_type basic_streambuf<_CharT, _Tra
 
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_streambuf<char>;
 
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 extern template class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_streambuf<wchar_t>;
-#endif
+#  endif
 
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #  include <cstdint>
 #endif
diff --git a/libcxx/include/syncstream b/libcxx/include/syncstream
index fea4c66b8e118..fe9aa07fcdaa8 100644
--- a/libcxx/include/syncstream
+++ b/libcxx/include/syncstream
@@ -118,33 +118,36 @@ namespace std {
 */
 
 #include <__config>
-#include <__utility/move.h>
-#include <ios>
-#include <iosfwd> // required for declaration of default arguments
-#include <streambuf>
-#include <string>
-
-#ifndef _LIBCPP_HAS_NO_THREADS
-#  include <map>
-#  include <mutex>
-#  include <shared_mutex>
-#endif
+
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
+#  include <__utility/move.h>
+#  include <ios>
+#  include <iosfwd> // required for declaration of default arguments
+#  include <streambuf>
+#  include <string>
+
+#  ifndef _LIBCPP_HAS_NO_THREADS
+#    include <map>
+#    include <mutex>
+#    include <shared_mutex>
+#  endif
 
 // standard-mandated includes
 
 // [syncstream.syn]
-#include <ostream>
+#  include <ostream>
 
-#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
-#  pragma GCC system_header
-#endif
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
 
 _LIBCPP_PUSH_MACROS
-#include <__undef_macros>
+#  include <__undef_macros>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
+#  if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
 
 // [syncstream.syncbuf.overview]/1
 //   Class template basic_syncbuf stores character data written to it,
@@ -157,7 +160,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 //
 // This helper singleton is used to implement the required
 // synchronisation guarantees.
-#  ifndef _LIBCPP_HAS_NO_THREADS
+#    ifndef _LIBCPP_HAS_NO_THREADS
 class __wrapped_streambuf_mutex {
   _LIBCPP_HIDE_FROM_ABI __wrapped_streambuf_mutex() = default;
 
@@ -230,7 +233,7 @@ private:
     return __it;
   }
 };
-#  endif // _LIBCPP_HAS_NO_THREADS
+#    endif // _LIBCPP_HAS_NO_THREADS
 
 // basic_syncbuf
 
@@ -270,14 +273,14 @@ public:
   }
 
   _LIBCPP_HIDE_FROM_ABI ~basic_syncbuf() {
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     try {
-#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#    endif // _LIBCPP_HAS_NO_EXCEPTIONS
       emit();
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
     } catch (...) {
     }
-#  endif // _LIBCPP_HAS_NO_EXCEPTIONS
+#    endif // _LIBCPP_HAS_NO_EXCEPTIONS
     __dec_reference();
   }
 
@@ -334,9 +337,9 @@ protected:
       return traits_type::not_eof(__c);
 
     if (this->pptr() == this->epptr()) {
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       try {
-#  endif
+#    endif
         size_t __size = __str_.size();
         __str_.resize(__str_.capacity() + 1);
         _LIBCPP_ASSERT_INTERNAL(__str_.size() > __size, "the buffer hasn't grown");
@@ -345,11 +348,11 @@ protected:
         this->setp(__p, __p + __str_.size());
         this->pbump(__size);
 
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       } catch (...) {
         return traits_type::eof();
       }
-#  endif
+#    endif
     }
 
     return this->sputc(traits_type::to_char_type(__c));
@@ -370,9 +373,9 @@ private:
     if (!__wrapped_)
       return false;
 
-#  ifndef _LIBCPP_HAS_NO_THREADS
+#    ifndef _LIBCPP_HAS_NO_THREADS
     lock_guard<mutex> __lock = __wrapped_streambuf_mutex::__instance().__get_lock(__wrapped_);
-#  endif
+#    endif
 
     bool __result = true;
     if (this->pptr() != this->pbase()) {
@@ -404,24 +407,24 @@ private:
   }
 
   _LIBCPP_HIDE_FROM_ABI void __inc_reference() {
-#  ifndef _LIBCPP_HAS_NO_THREADS
+#    ifndef _LIBCPP_HAS_NO_THREADS
     if (__wrapped_)
       __wrapped_streambuf_mutex::__instance().__inc_reference(__wrapped_);
-#  endif
+#    endif
   }
 
   _LIBCPP_HIDE_FROM_ABI void __dec_reference() noexcept {
-#  ifndef _LIBCPP_HAS_NO_THREADS
+#    ifndef _LIBCPP_HAS_NO_THREADS
     if (__wrapped_)
       __wrapped_streambuf_mutex::__instance().__dec_reference(__wrapped_);
-#  endif
+#    endif
   }
 };
 
 using std::syncbuf;
-#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 using std::wsyncbuf;
-#  endif
+#    endif
 
 // [syncstream.syncbuf.special], specialized algorithms
 template <class _CharT, class _Traits, class _Allocator>
@@ -477,17 +480,17 @@ public:
     // TODO validate other unformatted output functions.
     typename basic_ostream<char_type, traits_type>::sentry __s(*this);
     if (__s) {
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       try {
-#  endif
+#    endif
 
         if (__sb_.emit() == false)
           this->setstate(ios::badbit);
-#  ifndef _LIBCPP_HAS_NO_EXCEPTIONS
+#    ifndef _LIBCPP_HAS_NO_EXCEPTIONS
       } catch (...) {
         this->__set_badbit_and_consider_rethrow();
       }
-#  endif
+#    endif
     }
   }
 
@@ -502,14 +505,16 @@ private:
 };
 
 using std::osyncstream;
-#  ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
+#    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
 using std::wosyncstream;
-#  endif
+#    endif
 
-#endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
+#  endif // _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_EXPERIMENTAL_SYNCSTREAM)
 
 _LIBCPP_END_NAMESPACE_STD
 
 _LIBCPP_POP_MACROS
 
+#endif // !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
 #endif // _LIBCPP_SYNCSTREAM