Index: include/__bsd_locale_defaults.h
===================================================================
--- /dev/null
+++ include/__bsd_locale_defaults.h
@@ -0,0 +1,33 @@
+// -*- C++ -*-
+//===---------------------- __bsd_locale_defaults.h -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// The BSDs have lots of *_l functions.  We don't want to define those symbols
+// on other platforms though, for fear of conflicts with user code.  So here,
+// we will define the mapping from an internal macro to the real BSD symbol.
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_BSD_LOCALE_DEFAULTS_H
+#define _LIBCPP_BSD_LOCALE_DEFAULTS_H
+
+#define __libcpp_mb_cur_max_l(loc)                          MB_CUR_MAX_L(loc)
+#define __libcpp_btowc_l(ch, loc)                           btowc_l(ch, loc)
+#define __libcpp_wctob_l(wch, loc)                          wctob_l(wch, loc)
+#define __libcpp_wcsnrtombs_l(dst, src, nwc, len, ps, loc)  wcsnrtombs_l(dst, src, nwc, len, ps, loc)
+#define __libcpp_wcrtomb_l(src, wc, ps, loc)                wcrtomb_l(src, wc, ps, loc)
+#define __libcpp_mbsnrtowcs_l(dst, src, nms, len, ps, loc)  mbsnrtowcs_l(dst, src, nms, len, ps, loc)
+#define __libcpp_mbrtowc_l(pwc, s, n, ps, l)                mbrtowc_l(pwc, s, n, ps, l)
+#define __libcpp_mbtowc_l(pwc, pmb, max, l)                 mbtowc_l(pwc, pmb, max, l)
+#define __libcpp_mbrlen_l(s, n, ps, l)                      mbrlen_l(s, n, ps, l)
+#define __libcpp_localeconv_l(l)                            localeconv_l(l)
+#define __libcpp_mbsrtowcs_l(dest, src, len, ps, l)         mbsrtowcs_l(dest, src, len, ps, l)
+#define __libcpp_snprintf_l(...)                            snprintf_l(__VA_ARGS__)
+#define __libcpp_asprintf_l(...)                            asprintf_l(__VA_ARGS__)
+#define __libcpp_sscanf_l(...)                              sscanf_l(__VA_ARGS__)
+
+#endif // _LIBCPP_BSD_LOCALE_DEFAULTS_H
Index: include/__bsd_locale_fallbacks.h
===================================================================
--- /dev/null
+++ include/__bsd_locale_fallbacks.h
@@ -0,0 +1,138 @@
+// -*- C++ -*-
+//===---------------------- __bsd_locale_fallbacks.h ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// The BSDs have lots of *_l functions.  This file provides reimplementations
+// of those functions for non-BSD platforms.
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_BSD_LOCALE_FALLBACKS_DEFAULTS_H
+#define _LIBCPP_BSD_LOCALE_FALLBACKS_DEFAULTS_H
+
+#include <stdlib.h>
+#include <memory>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+typedef _VSTD::remove_pointer<locale_t>::type __use_locale_struct;
+typedef _VSTD::unique_ptr<__use_locale_struct, decltype(&uselocale)> __locale_raii;
+
+inline _LIBCPP_ALWAYS_INLINE
+decltype(MB_CUR_MAX) __libcpp_mb_cur_max_l(locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return MB_CUR_MAX;
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+wint_t __libcpp_btowc_l(int __c, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return btowc(__c);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_wctob_l(wint_t __c, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return wctob(__c);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+size_t __libcpp_wcsnrtombs_l(char *__dest, const wchar_t **__src, size_t __nwc,
+                         size_t __len, mbstate_t *__ps, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return wcsnrtombs(__dest, __src, __nwc, __len, __ps);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+size_t __libcpp_wcrtomb_l(char *__s, wchar_t __wc, mbstate_t *__ps, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return wcrtomb(__s, __wc, __ps);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+size_t __libcpp_mbsnrtowcs_l(wchar_t * __dest, const char **__src, size_t __nms,
+                      size_t __len, mbstate_t *__ps, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return mbsnrtowcs(__dest, __src, __nms, __len, __ps);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+size_t __libcpp_mbrtowc_l(wchar_t *__pwc, const char *__s, size_t __n,
+                   mbstate_t *__ps, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return mbrtowc(__pwc, __s, __n, __ps);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+int __libcpp_mbtowc_l(wchar_t *__pwc, const char *__pmb, size_t __max, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return mbtowc(__pwc, __pmb, __max);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+size_t __libcpp_mbrlen_l(const char *__s, size_t __n, mbstate_t *__ps, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return mbrlen(__s, __n, __ps);
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+lconv *__libcpp_localeconv_l(locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return localeconv();
+}
+
+inline _LIBCPP_ALWAYS_INLINE
+size_t __libcpp_mbsrtowcs_l(wchar_t *__dest, const char **__src, size_t __len,
+                     mbstate_t *__ps, locale_t __l)
+{
+    __locale_raii __current( uselocale(__l), uselocale );
+    return mbsrtowcs(__dest, __src, __len, __ps);
+}
+
+inline
+int __libcpp_snprintf_l(char *__s, size_t __n, locale_t __l, const char *__format, ...) {
+    va_list __va;
+    va_start(__va, __format);
+    __locale_raii __current( uselocale(__l), uselocale );
+    int __res = vsnprintf(__s, __n, __format, __va);
+    va_end(__va);
+    return __res;
+}
+
+inline
+int __libcpp_asprintf_l(char **__s, locale_t __l, const char *__format, ...) {
+    va_list __va;
+    va_start(__va, __format);
+    __locale_raii __current( uselocale(__l), uselocale );
+    int __res = vasprintf(__s, __format, __va);
+    va_end(__va);
+    return __res;
+}
+
+inline
+int __libcpp_sscanf_l(const char *__s, locale_t __l, const char *__format, ...) {
+    va_list __va;
+    va_start(__va, __format);
+    __locale_raii __current( uselocale(__l), uselocale );
+    int __res = vsscanf(__s, __format, __va);
+    va_end(__va);
+    return __res;
+}
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_BSD_LOCALE_FALLBACKS_DEFAULTS_H
Index: include/locale
===================================================================
--- include/locale
+++ include/locale
@@ -213,6 +213,12 @@
 #pragma GCC system_header
 #endif
 
+#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
+#include <__bsd_locale_defaults.h>
+#else
+#include <__bsd_locale_fallbacks.h>
+#endif
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if defined(__APPLE__) || defined(__FreeBSD__)
@@ -228,189 +234,6 @@
 
 typedef _VSTD::remove_pointer<locale_t>::type __locale_struct;
 typedef _VSTD::unique_ptr<__locale_struct, decltype(&freelocale)> __locale_unique_ptr;
-#ifndef _LIBCPP_LOCALE__L_EXTENSIONS
-typedef _VSTD::unique_ptr<__locale_struct, decltype(&uselocale)> __locale_raii;
-#endif
-
-// OSX has nice foo_l() functions that let you turn off use of the global
-// locale.  Linux, not so much.  The following functions avoid the locale when
-// that's possible and otherwise do the wrong thing.  FIXME.
-#if defined(__linux__) || defined(__EMSCRIPTEN__) || defined(_AIX) || \
-    defined(_NEWLIB_VERSION) || defined(__GLIBC__)
-
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-decltype(MB_CUR_MAX_L(_VSTD::declval<locale_t>()))
-inline _LIBCPP_INLINE_VISIBILITY
-__mb_cur_max_l(locale_t __l)
-{
-  return MB_CUR_MAX_L(__l);
-}
-#else  // _LIBCPP_LOCALE__L_EXTENSIONS
-inline _LIBCPP_ALWAYS_INLINE
-decltype(MB_CUR_MAX) __mb_cur_max_l(locale_t __l)
-{
-  __locale_raii __current(uselocale(__l), uselocale);
-  return MB_CUR_MAX;
-}
-#endif // _LIBCPP_LOCALE__L_EXTENSIONS
-
-inline _LIBCPP_ALWAYS_INLINE
-wint_t __btowc_l(int __c, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return btowc_l(__c, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return btowc(__c);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-int __wctob_l(wint_t __c, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return wctob_l(__c, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return wctob(__c);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-size_t __wcsnrtombs_l(char *__dest, const wchar_t **__src, size_t __nwc,
-                      size_t __len, mbstate_t *__ps, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return wcsnrtombs_l(__dest, __src, __nwc, __len, __ps, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return wcsnrtombs(__dest, __src, __nwc, __len, __ps);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-size_t __wcrtomb_l(char *__s, wchar_t __wc, mbstate_t *__ps, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return wcrtomb_l(__s, __wc, __ps, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return wcrtomb(__s, __wc, __ps);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-size_t __mbsnrtowcs_l(wchar_t * __dest, const char **__src, size_t __nms,
-                      size_t __len, mbstate_t *__ps, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return mbsnrtowcs_l(__dest, __src, __nms, __len, __ps, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return mbsnrtowcs(__dest, __src, __nms, __len, __ps);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-size_t __mbrtowc_l(wchar_t *__pwc, const char *__s, size_t __n,
-                   mbstate_t *__ps, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return mbrtowc_l(__pwc, __s, __n, __ps, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return mbrtowc(__pwc, __s, __n, __ps);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-int __mbtowc_l(wchar_t *__pwc, const char *__pmb, size_t __max, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return mbtowc_l(__pwc, __pmb, __max, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return mbtowc(__pwc, __pmb, __max);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-size_t __mbrlen_l(const char *__s, size_t __n, mbstate_t *__ps, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return mbrlen_l(__s, __n, __ps, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return mbrlen(__s, __n, __ps);
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-lconv *__localeconv_l(locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return localeconv_l(__l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return localeconv();
-#endif
-}
-
-inline _LIBCPP_ALWAYS_INLINE
-size_t __mbsrtowcs_l(wchar_t *__dest, const char **__src, size_t __len,
-                     mbstate_t *__ps, locale_t __l)
-{
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  return mbsrtowcs_l(__dest, __src, __len, __ps, __l);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  return mbsrtowcs(__dest, __src, __len, __ps);
-#endif
-}
-
-inline
-int __snprintf_l(char *__s, size_t __n, locale_t __l, const char *__format, ...) {
-  va_list __va;
-  va_start(__va, __format);
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  int __res = vsnprintf_l(__s, __n, __l, __format, __va);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  int __res = vsnprintf(__s, __n, __format, __va);
-#endif
-  va_end(__va);
-  return __res;
-}
-
-inline
-int __asprintf_l(char **__s, locale_t __l, const char *__format, ...) {
-  va_list __va;
-  va_start(__va, __format);
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  int __res = vasprintf_l(__s, __l, __format, __va);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  int __res = vasprintf(__s, __format, __va);
-#endif
-  va_end(__va);
-  return __res;
-}
-
-inline
-int __sscanf_l(const char *__s, locale_t __l, const char *__format, ...) {
-  va_list __va;
-  va_start(__va, __format);
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-  int __res = vsscanf_l(__s, __l, __format, __va);
-#else
-  __locale_raii __current(uselocale(__l), uselocale);
-  int __res = vsscanf(__s, __format, __va);
-#endif
-  va_end(__va);
-  return __res;
-}
-
-#endif  // __linux__
 
 // __scan_keyword
 // Scans [__b, __e) until a match is found in the basic_strings range
@@ -1188,11 +1011,7 @@
     }
     // Stage 3
     __buf.resize(__a_end - __a);
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    if (sscanf_l(__buf.c_str(), _LIBCPP_GET_C_LOCALE, "%p", &__v) != 1)
-#else
-    if (__sscanf_l(__buf.c_str(), _LIBCPP_GET_C_LOCALE, "%p", &__v) != 1)
-#endif
+    if (__libcpp_sscanf_l(__buf.c_str(), _LIBCPP_GET_C_LOCALE, "%p", &__v) != 1)
         __err = ios_base::failbit;
     // EOF checked
     if (__b == __e)
@@ -1558,11 +1377,7 @@
                           + ((numeric_limits<long>::digits % 3) != 0)
                           + 1;
     char __nar[__nbuf];
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    int __nc = snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-    int __nc = __snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+    int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
     char* __ne = __nar + __nc;
     char* __np = this->__identify_padding(__nar, __ne, __iob);
     // Stage 2 - Widen __nar while adding thousands separators
@@ -1588,11 +1403,7 @@
                           + ((numeric_limits<long long>::digits % 3) != 0)
                           + 2;
     char __nar[__nbuf];
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    int __nc = snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-    int __nc = __snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+    int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
     char* __ne = __nar + __nc;
     char* __np = this->__identify_padding(__nar, __ne, __iob);
     // Stage 2 - Widen __nar while adding thousands separators
@@ -1618,11 +1429,7 @@
                           + ((numeric_limits<unsigned long>::digits % 3) != 0)
                           + 1;
     char __nar[__nbuf];
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    int __nc = snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-    int __nc = __snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+    int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
     char* __ne = __nar + __nc;
     char* __np = this->__identify_padding(__nar, __ne, __iob);
     // Stage 2 - Widen __nar while adding thousands separators
@@ -1648,11 +1455,7 @@
                           + ((numeric_limits<unsigned long long>::digits % 3) != 0)
                           + 1;
     char __nar[__nbuf];
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    int __nc = snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-    int __nc = __snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+    int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
     char* __ne = __nar + __nc;
     char* __np = this->__identify_padding(__nar, __ne, __iob);
     // Stage 2 - Widen __nar while adding thousands separators
@@ -1679,34 +1482,17 @@
     char* __nb = __nar;
     int __nc;
     if (__specify_precision)
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        __nc = snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt,
-                                   (int)__iob.precision(), __v);
-#else
-        __nc = __snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt,
+        __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt,
                                    (int)__iob.precision(), __v);
-#endif
     else
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        __nc = snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-        __nc = __snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+        __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
     unique_ptr<char, void(*)(void*)> __nbh(0, free);
     if (__nc > static_cast<int>(__nbuf-1))
     {
         if (__specify_precision)
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-            __nc = asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
-#else
-            __nc = __asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
-#endif
+            __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
         else
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-            __nc = asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-            __nc = __asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
-#endif
+            __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
         if (__nb == 0)
             __throw_bad_alloc();
         __nbh.reset(__nb);
@@ -1747,34 +1533,17 @@
     char* __nb = __nar;
     int __nc;
     if (__specify_precision)
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        __nc = snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt,
-                                   (int)__iob.precision(), __v);
-#else
-        __nc = __snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt,
+        __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt,
                                    (int)__iob.precision(), __v);
-#endif
     else
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        __nc = snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-        __nc = __snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+        __nc = __libcpp_snprintf_l(__nb, __nbuf, _LIBCPP_GET_C_LOCALE, __fmt, __v);
     unique_ptr<char, void(*)(void*)> __nbh(0, free);
     if (__nc > static_cast<int>(__nbuf-1))
     {
         if (__specify_precision)
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-            __nc = asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
-#else
-            __nc = __asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
-#endif
+            __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, (int)__iob.precision(), __v);
         else
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-            __nc = asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-            __nc = __asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+            __nc = __libcpp_asprintf_l(&__nb, _LIBCPP_GET_C_LOCALE, __fmt, __v);
         if (__nb == 0)
             __throw_bad_alloc();
         __nbh.reset(__nb);
@@ -1810,11 +1579,7 @@
     char __fmt[6] = "%p";
     const unsigned __nbuf = 20;
     char __nar[__nbuf];
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    int __nc = snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#else
-    int __nc = __snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
-#endif
+    int __nc = __libcpp_snprintf_l(__nar, sizeof(__nar), _LIBCPP_GET_C_LOCALE, __fmt, __v);
     char* __ne = __nar + __nc;
     char* __np = this->__identify_padding(__nar, __ne, __iob);
     // Stage 2 - Widen __nar
@@ -3526,11 +3291,7 @@
     // secure memory for digit storage
     if (__n > __bs-1)
     {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        __n = static_cast<size_t>(asprintf_l(&__bb, _LIBCPP_GET_C_LOCALE, "%.0Lf", __units));
-#else
-        __n = __asprintf_l(&__bb, _LIBCPP_GET_C_LOCALE, "%.0Lf", __units);
-#endif
+        __n = static_cast<size_t>(__libcpp_asprintf_l(&__bb, _LIBCPP_GET_C_LOCALE, "%.0Lf", __units));
         if (__bb == 0)
             __throw_bad_alloc();
         __hn.reset(__bb);
Index: src/locale.cpp
===================================================================
--- src/locale.cpp
+++ src/locale.cpp
@@ -1400,33 +1400,21 @@
 wchar_t
 ctype_byname<wchar_t>::do_widen(char c) const
 {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    return btowc_l(c, __l);
-#else
-    return __btowc_l(c, __l);
-#endif
+    return __libcpp_btowc_l(c, __l);
 }
 
 const char*
 ctype_byname<wchar_t>::do_widen(const char* low, const char* high, char_type* dest) const
 {
     for (; low != high; ++low, ++dest)
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        *dest = btowc_l(*low, __l);
-#else
-        *dest = __btowc_l(*low, __l);
-#endif
+        *dest = __libcpp_btowc_l(*low, __l);
     return low;
 }
 
 char
 ctype_byname<wchar_t>::do_narrow(char_type c, char dfault) const
 {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    int r = wctob_l(c, __l);
-#else
-    int r = __wctob_l(c, __l);
-#endif
+    int r = __libcpp_wctob_l(c, __l);
     return r != static_cast<int>(WEOF) ? static_cast<char>(r) : dfault;
 }
 
@@ -1435,11 +1423,7 @@
 {
     for (; low != high; ++low, ++dest)
     {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        int r = wctob_l(*low, __l);
-#else
-        int r = __wctob_l(*low, __l);
-#endif
+        int r = __libcpp_wctob_l(*low, __l);
         *dest = r != static_cast<int>(WEOF) ? static_cast<char>(r) : dfault;
     }
     return low;
@@ -1549,22 +1533,14 @@
     {
         // save state in case it is needed to recover to_nxt on error
         mbstate_t save_state = st;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        size_t n = wcsnrtombs_l(to, &frm_nxt, static_cast<size_t>(fend-frm),
-                                static_cast<size_t>(to_end-to), &st, __l);
-#else
-        size_t n = __wcsnrtombs_l(to, &frm_nxt, fend-frm, to_end-to, &st, __l);
-#endif
+        size_t n = __libcpp_wcsnrtombs_l(to, &frm_nxt, static_cast<size_t>(fend-frm),
+                                     static_cast<size_t>(to_end-to), &st, __l);
         if (n == size_t(-1))
         {
             // need to recover to_nxt
             for (to_nxt = to; frm != frm_nxt; ++frm)
             {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-                n = wcrtomb_l(to_nxt, *frm, &save_state, __l);
-#else
-                n = __wcrtomb_l(to_nxt, *frm, &save_state, __l);
-#endif
+                n = __libcpp_wcrtomb_l(to_nxt, *frm, &save_state, __l);
                 if (n == size_t(-1))
                     break;
                 to_nxt += n;
@@ -1581,11 +1557,7 @@
         {
             // Try to write the terminating null
             extern_type tmp[MB_LEN_MAX];
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-            n = wcrtomb_l(tmp, intern_type(), &st, __l);
-#else
-            n = __wcrtomb_l(tmp, intern_type(), &st, __l);
-#endif
+            n = __libcpp_wcrtomb_l(tmp, intern_type(), &st, __l);
             if (n == size_t(-1))  // on error
                 return error;
             if (n > static_cast<size_t>(to_end-to_nxt))  // is there room?
@@ -1618,23 +1590,15 @@
     {
         // save state in case it is needed to recover to_nxt on error
         mbstate_t save_state = st;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        size_t n = mbsnrtowcs_l(to, &frm_nxt, static_cast<size_t>(fend-frm),
-                                static_cast<size_t>(to_end-to), &st, __l);
-#else
-        size_t n = __mbsnrtowcs_l(to, &frm_nxt, fend-frm, to_end-to, &st, __l);
-#endif
+        size_t n = __libcpp_mbsnrtowcs_l(to, &frm_nxt, static_cast<size_t>(fend-frm),
+                                     static_cast<size_t>(to_end-to), &st, __l);
         if (n == size_t(-1))
         {
             // need to recover to_nxt
             for (to_nxt = to; frm != frm_nxt; ++to_nxt)
             {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-                n = mbrtowc_l(to_nxt, frm, static_cast<size_t>(fend-frm),
-                              &save_state, __l);
-#else
-                n = __mbrtowc_l(to_nxt, frm, fend-frm, &save_state, __l);
-#endif
+                n = __libcpp_mbrtowc_l(to_nxt, frm, static_cast<size_t>(fend-frm),
+                                   &save_state, __l);
                 switch (n)
                 {
                 case 0:
@@ -1662,11 +1626,7 @@
         if (fend != frm_end)  // set up next null terminated sequence
         {
             // Try to write the terminating null
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-            n = mbrtowc_l(to_nxt, frm_nxt, 1, &st, __l);
-#else
-            n = __mbrtowc_l(to_nxt, frm_nxt, 1, &st, __l);
-#endif
+            n = __libcpp_mbrtowc_l(to_nxt, frm_nxt, 1, &st, __l);
             if (n != 0)  // on error
                 return error;
             ++to_nxt;
@@ -1686,11 +1646,7 @@
 {
     to_nxt = to;
     extern_type tmp[MB_LEN_MAX];
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    size_t n = wcrtomb_l(tmp, intern_type(), &st, __l);
-#else
-    size_t n = __wcrtomb_l(tmp, intern_type(), &st, __l);
-#endif
+    size_t n = __libcpp_wcrtomb_l(tmp, intern_type(), &st, __l);
     if (n == size_t(-1) || n == 0)  // on error
         return error;
     --n;
@@ -1705,20 +1661,12 @@
 codecvt<wchar_t, char, mbstate_t>::do_encoding() const  _NOEXCEPT
 {
 #ifndef __CloudABI__
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    if (mbtowc_l(nullptr, nullptr, MB_LEN_MAX, __l) != 0)
-#else
-    if (__mbtowc_l(nullptr, nullptr, MB_LEN_MAX, __l) != 0)
-#endif
+    if (__libcpp_mbtowc_l(nullptr, nullptr, MB_LEN_MAX, __l) != 0)
         return -1;
 #endif
 
     // stateless encoding
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    if (__l == 0 || MB_CUR_MAX_L(__l) == 1)  // there are no known constant length encodings
-#else
-    if (__l == 0 || __mb_cur_max_l(__l) == 1)  // there are no known constant length encodings
-#endif
+    if (__l == 0 || __libcpp_mb_cur_max_l(__l) == 1)  // there are no known constant length encodings
         return 1;                // which take more than 1 char to form a wchar_t
     return 0;
 }
@@ -1736,11 +1684,7 @@
     int nbytes = 0;
     for (size_t nwchar_t = 0; nwchar_t < mx && frm != frm_end; ++nwchar_t)
     {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        size_t n = mbrlen_l(frm, static_cast<size_t>(frm_end-frm), &st, __l);
-#else
-        size_t n = __mbrlen_l(frm, frm_end-frm, &st, __l);
-#endif
+        size_t n = __libcpp_mbrlen_l(frm, static_cast<size_t>(frm_end-frm), &st, __l);
         switch (n)
         {
         case 0:
@@ -1762,11 +1706,7 @@
 int
 codecvt<wchar_t, char, mbstate_t>::do_max_length() const  _NOEXCEPT
 {
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    return __l == 0 ? 1 : static_cast<int>(  MB_CUR_MAX_L(__l));
-#else
-    return __l == 0 ? 1 : static_cast<int>(__mb_cur_max_l(__l));
-#endif
+    return __l == 0 ? 1 : static_cast<int>(__libcpp_mb_cur_max_l(__l));
 }
 
 //                                     Valid UTF ranges
@@ -4324,11 +4264,7 @@
             throw runtime_error("numpunct_byname<char>::numpunct_byname"
                                 " failed to construct for " + string(nm));
 #endif  // _LIBCPP_NO_EXCEPTIONS
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        lconv* lc = localeconv_l(loc.get());
-#else
-        lconv* lc = __localeconv_l(loc.get());
-#endif
+        lconv* lc = __libcpp_localeconv_l(loc.get());
         if (*lc->decimal_point)
             __decimal_point_ = *lc->decimal_point;
         if (*lc->thousands_sep)
@@ -4367,11 +4303,7 @@
             throw runtime_error("numpunct_byname<char>::numpunct_byname"
                                 " failed to construct for " + string(nm));
 #endif  // _LIBCPP_NO_EXCEPTIONS
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        lconv* lc = localeconv_l(loc.get());
-#else
-        lconv* lc = __localeconv_l(loc.get());
-#endif
+        lconv* lc = __libcpp_localeconv_l(loc.get());
         if (*lc->decimal_point)
             __decimal_point_ = *lc->decimal_point;
         if (*lc->thousands_sep)
@@ -4972,11 +4904,7 @@
     wchar_t* wbb = wbuf;
     mbstate_t mb = {0};
     const char* bb = buf;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    size_t j = mbsrtowcs_l( wbb, &bb, countof(wbuf), &mb, __loc_);
-#else
-    size_t j = __mbsrtowcs_l( wbb, &bb, countof(wbuf), &mb, __loc_);
-#endif
+    size_t j = __libcpp_mbsrtowcs_l( wbb, &bb, countof(wbuf), &mb, __loc_);
     if (j == size_t(-1))
         __throw_runtime_error("locale not supported");
     wchar_t* wbe = wbb + j;
@@ -5156,11 +5084,7 @@
         strftime_l(buf, countof(buf), "%A", &t, __loc_);
         mb = mbstate_t();
         const char* bb = buf;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        size_t j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#else
-        size_t j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#endif
+        size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;
@@ -5168,11 +5092,7 @@
         strftime_l(buf, countof(buf), "%a", &t, __loc_);
         mb = mbstate_t();
         bb = buf;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#else
-        j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#endif
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;
@@ -5185,11 +5105,7 @@
         strftime_l(buf, countof(buf), "%B", &t, __loc_);
         mb = mbstate_t();
         const char* bb = buf;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        size_t j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#else
-        size_t j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#endif
+        size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;
@@ -5197,11 +5113,7 @@
         strftime_l(buf, countof(buf), "%b", &t, __loc_);
         mb = mbstate_t();
         bb = buf;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#else
-        j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#endif
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;
@@ -5212,11 +5124,7 @@
     strftime_l(buf, countof(buf), "%p", &t, __loc_);
     mb = mbstate_t();
     const char* bb = buf;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    size_t j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#else
-    size_t j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#endif
+    size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
     if (j == size_t(-1))
         __throw_runtime_error("locale not supported");
     wbe = wbuf + j;
@@ -5225,11 +5133,7 @@
     strftime_l(buf, countof(buf), "%p", &t, __loc_);
     mb = mbstate_t();
     bb = buf;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#else
-    j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
-#endif
+    j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, __loc_);
     if (j == size_t(-1))
         __throw_runtime_error("locale not supported");
     wbe = wbuf + j;
@@ -5504,11 +5408,7 @@
     __do_put(__nar, __ne, __tm, __fmt, __mod);
     mbstate_t mb = {0};
     const char* __nb = __nar;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    size_t j = mbsrtowcs_l(__wb, &__nb, countof(__wb, __we), &mb, __loc_);
-#else
-    size_t j = __mbsrtowcs_l(__wb, &__nb, countof(__wb, __we), &mb, __loc_);
-#endif
+    size_t j = __libcpp_mbsrtowcs_l(__wb, &__nb, countof(__wb, __we), &mb, __loc_);
     if (j == size_t(-1))
         __throw_runtime_error("locale not supported");
     __we = __wb + j;
@@ -5899,11 +5799,7 @@
         throw runtime_error("moneypunct_byname"
                             " failed to construct for " + string(nm));
 #endif  // _LIBCPP_NO_EXCEPTIONS
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    lconv* lc = localeconv_l(loc.get());
-#else
-    lconv* lc = __localeconv_l(loc.get());
-#endif
+    lconv* lc = __libcpp_localeconv_l(loc.get());
     if (*lc->mon_decimal_point)
         __decimal_point_ = *lc->mon_decimal_point;
     else
@@ -5947,11 +5843,7 @@
         throw runtime_error("moneypunct_byname"
                             " failed to construct for " + string(nm));
 #endif  // _LIBCPP_NO_EXCEPTIONS
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    lconv* lc = localeconv_l(loc.get());
-#else
-    lconv* lc = __localeconv_l(loc.get());
-#endif
+    lconv* lc = __libcpp_localeconv_l(loc.get());
     if (*lc->mon_decimal_point)
         __decimal_point_ = *lc->mon_decimal_point;
     else
@@ -6012,11 +5904,7 @@
         throw runtime_error("moneypunct_byname"
                             " failed to construct for " + string(nm));
 #endif  // _LIBCPP_NO_EXCEPTIONS
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    lconv* lc = localeconv_l(loc.get());
-#else
-    lconv* lc = __localeconv_l(loc.get());
-#endif
+    lconv* lc = __libcpp_localeconv_l(loc.get());
     if (*lc->mon_decimal_point)
         __decimal_point_ = static_cast<wchar_t>(*lc->mon_decimal_point);
     else
@@ -6029,11 +5917,7 @@
     wchar_t wbuf[100];
     mbstate_t mb = {0};
     const char* bb = lc->currency_symbol;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    size_t j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#else
-    size_t j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#endif
+    size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
     if (j == size_t(-1))
         __throw_runtime_error("locale not supported");
     wchar_t* wbe = wbuf + j;
@@ -6048,11 +5932,7 @@
     {
         mb = mbstate_t();
         bb = lc->positive_sign;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#else
-        j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#endif
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;
@@ -6064,11 +5944,7 @@
     {
         mb = mbstate_t();
         bb = lc->negative_sign;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#else
-        j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#endif
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;
@@ -6095,11 +5971,7 @@
         throw runtime_error("moneypunct_byname"
                             " failed to construct for " + string(nm));
 #endif  // _LIBCPP_NO_EXCEPTIONS
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    lconv* lc = localeconv_l(loc.get());
-#else
-    lconv* lc = __localeconv_l(loc.get());
-#endif
+    lconv* lc = __libcpp_localeconv_l(loc.get());
     if (*lc->mon_decimal_point)
         __decimal_point_ = static_cast<wchar_t>(*lc->mon_decimal_point);
     else
@@ -6112,11 +5984,7 @@
     wchar_t wbuf[100];
     mbstate_t mb = {0};
     const char* bb = lc->int_curr_symbol;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-    size_t j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#else
-    size_t j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#endif
+    size_t j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
     if (j == size_t(-1))
         __throw_runtime_error("locale not supported");
     wchar_t* wbe = wbuf + j;
@@ -6135,11 +6003,7 @@
     {
         mb = mbstate_t();
         bb = lc->positive_sign;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#else
-        j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#endif
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;
@@ -6155,11 +6019,7 @@
     {
         mb = mbstate_t();
         bb = lc->negative_sign;
-#ifdef _LIBCPP_LOCALE__L_EXTENSIONS
-        j = mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#else
-        j = __mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
-#endif
+        j = __libcpp_mbsrtowcs_l(wbuf, &bb, countof(wbuf), &mb, loc.get());
         if (j == size_t(-1))
             __throw_runtime_error("locale not supported");
         wbe = wbuf + j;