Index: libcxx/include/__config
===================================================================
--- libcxx/include/__config
+++ libcxx/include/__config
@@ -59,6 +59,7 @@
 // `pointer_safety` and `get_pointer_safety()` will no longer be available
 // in C++03.
 #define _LIBCPP_ABI_POINTER_SAFETY_ENUM_TYPE
+#define _LIBCPP_ABI_OPTIMIZED_LOCALE
 #elif _LIBCPP_ABI_VERSION == 1
 #if !defined(_WIN32)
 // Enable compiling copies of now inline methods into the dylib to support
Index: libcxx/include/locale
===================================================================
--- libcxx/include/locale
+++ libcxx/include/locale
@@ -380,19 +380,57 @@
 struct __num_get
     : protected __num_get_base
 {
-    static string __stage2_int_prep(ios_base& __iob, _CharT* __atoms, _CharT& __thousands_sep);
     static string __stage2_float_prep(ios_base& __iob, _CharT* __atoms, _CharT& __decimal_point,
                                       _CharT& __thousands_sep);
-    static int __stage2_int_loop(_CharT __ct, int __base, char* __a, char*& __a_end,
-                  unsigned& __dc, _CharT __thousands_sep, const string& __grouping,
-                  unsigned* __g, unsigned*& __g_end, _CharT* __atoms);
+
     static int __stage2_float_loop(_CharT __ct, bool& __in_units, char& __exp,
                                    char* __a, char*& __a_end,
                                    _CharT __decimal_point, _CharT __thousands_sep,
                                    const string& __grouping, unsigned* __g,
                                    unsigned*& __g_end, unsigned& __dc, _CharT* __atoms);
+#ifndef _LIBCPP_ABI_OPTIMIZED_LOCALE
+    static string __stage2_int_prep(ios_base& __iob, _CharT* __atoms, _CharT& __thousands_sep);
+    static int __stage2_int_loop(_CharT __ct, int __base, char* __a, char*& __a_end,
+                  unsigned& __dc, _CharT __thousands_sep, const string& __grouping,
+                  unsigned* __g, unsigned*& __g_end, _CharT* __atoms);
+
+#else
+    static string __stage2_int_prep(ios_base& __iob, _CharT& __thousands_sep)
+    {
+        locale __loc = __iob.getloc();
+        const numpunct<_CharT>& __np = use_facet<numpunct<_CharT> >(__loc);
+        __thousands_sep = __np.thousands_sep();
+        return __np.grouping();
+    }
+
+    const _CharT* __do_widen(ios_base& __iob, _CharT* __atoms) const
+    {
+      return __do_widen_p(__iob, __atoms);
+    }
+
+
+    static int __stage2_int_loop(_CharT __ct, int __base, char* __a, char*& __a_end,
+                  unsigned& __dc, _CharT __thousands_sep, const string& __grouping,
+                  unsigned* __g, unsigned*& __g_end, const _CharT* __atoms);
+private:
+    template<typename T>
+    const T* __do_widen_p(ios_base& __iob, T* __atoms) const
+    {
+      locale __loc = __iob.getloc();
+      use_facet<ctype<T> >(__loc).widen(__src, __src + 26, __atoms);
+      return __atoms;
+    }
+
+    const char* __do_widen_p(ios_base& __iob, char* __atoms) const
+    {
+      (void)__iob;
+      (void)__atoms;
+      return __src;
+    }
+#endif
 };
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_LOCALE
 template <class _CharT>
 string
 __num_get<_CharT>::__stage2_int_prep(ios_base& __iob, _CharT* __atoms, _CharT& __thousands_sep)
@@ -403,6 +441,7 @@
     __thousands_sep = __np.thousands_sep();
     return __np.grouping();
 }
+#endif
 
 template <class _CharT>
 string
@@ -419,9 +458,17 @@
 
 template <class _CharT>
 int
+#ifndef _LIBCPP_ABI_OPTIMIZED_LOCALE
 __num_get<_CharT>::__stage2_int_loop(_CharT __ct, int __base, char* __a, char*& __a_end,
                   unsigned& __dc, _CharT __thousands_sep, const string& __grouping,
                   unsigned* __g, unsigned*& __g_end, _CharT* __atoms)
+#else
+__num_get<_CharT>::__stage2_int_loop(_CharT __ct, int __base, char* __a, char*& __a_end,
+                  unsigned& __dc, _CharT __thousands_sep, const string& __grouping,
+                  unsigned* __g, unsigned*& __g_end, const _CharT* __atoms)
+
+#endif
+
 {
     if (__a_end == __a && (__ct == __atoms[24] || __ct == __atoms[25]))
     {
@@ -841,6 +888,7 @@
     return __b;
 }
 
+#ifndef _LIBCPP_ABI_OPTIMIZED_LOCALE
 // signed
 
 template <class _CharT, class _InputIterator>
@@ -941,6 +989,110 @@
     return __b;
 }
 
+#else
+//signed
+
+template <class _CharT, class _InputIterator>
+template <class _Signed>
+_InputIterator
+num_get<_CharT, _InputIterator>::__do_get_signed(iter_type __b, iter_type __e,
+                                        ios_base& __iob,
+                                        ios_base::iostate& __err,
+                                        _Signed& __v) const
+{
+    // Stage 1
+    int __base = this->__get_base(__iob);
+    // Stage 2
+    char_type __atoms1[26];
+    char_type __thousands_sep;
+    const char_type *__atoms = this->__do_widen(__iob, __atoms1);
+    string __grouping = this->__stage2_int_prep(__iob, __thousands_sep);
+    string __buf;
+    __buf.resize(__buf.capacity());
+    char* __a = &__buf[0];
+    char* __a_end = __a;
+    unsigned __g[__num_get_base::__num_get_buf_sz];
+    unsigned* __g_end = __g;
+    unsigned __dc = 0;
+    for (; __b != __e; ++__b)
+    {
+        if (__a_end == __a + __buf.size())
+        {
+            size_t __tmp = __buf.size();
+            __buf.resize(2*__buf.size());
+            __buf.resize(__buf.capacity());
+            __a = &__buf[0];
+            __a_end = __a + __tmp;
+        }
+        if (this->__stage2_int_loop(*__b, __base, __a, __a_end, __dc,
+                                    __thousands_sep, __grouping, __g, __g_end,
+                                    __atoms))
+            break;
+    }
+    if (__grouping.size() != 0 && __g_end-__g < __num_get_base::__num_get_buf_sz)
+        *__g_end++ = __dc;
+    // Stage 3
+    __v = __num_get_signed_integral<_Signed>(__a, __a_end, __err, __base);
+    // Digit grouping checked
+    __check_grouping(__grouping, __g, __g_end, __err);
+    // EOF checked
+    if (__b == __e)
+        __err |= ios_base::eofbit;
+    return __b;
+}
+
+// unsigned
+
+template <class _CharT, class _InputIterator>
+template <class _Unsigned>
+_InputIterator
+num_get<_CharT, _InputIterator>::__do_get_unsigned(iter_type __b, iter_type __e,
+                                        ios_base& __iob,
+                                        ios_base::iostate& __err,
+                                        _Unsigned& __v) const
+{
+    // Stage 1
+    int __base = this->__get_base(__iob);
+    // Stage 2
+    char_type __atoms1[26];
+    char_type __thousands_sep;
+    const char_type *__atoms = this->__do_widen(__iob, __atoms1);
+    string __grouping = this->__stage2_int_prep(__iob, __thousands_sep);
+    string __buf;
+    __buf.resize(__buf.capacity());
+    char* __a = &__buf[0];
+    char* __a_end = __a;
+    unsigned __g[__num_get_base::__num_get_buf_sz];
+    unsigned* __g_end = __g;
+    unsigned __dc = 0;
+    for (; __b != __e; ++__b)
+    {
+        if (__a_end == __a + __buf.size())
+        {
+            size_t __tmp = __buf.size();
+            __buf.resize(2*__buf.size());
+            __buf.resize(__buf.capacity());
+            __a = &__buf[0];
+            __a_end = __a + __tmp;
+        }
+        if (this->__stage2_int_loop(*__b, __base, __a, __a_end, __dc,
+                                    __thousands_sep, __grouping, __g, __g_end,
+                                    __atoms))
+            break;
+    }
+    if (__grouping.size() != 0 && __g_end-__g < __num_get_base::__num_get_buf_sz)
+        *__g_end++ = __dc;
+    // Stage 3
+    __v = __num_get_unsigned_integral<_Unsigned>(__a, __a_end, __err, __base);
+    // Digit grouping checked
+    __check_grouping(__grouping, __g, __g_end, __err);
+    // EOF checked
+    if (__b == __e)
+        __err |= ios_base::eofbit;
+    return __b;
+}
+#endif
+
 // floating point
 
 template <class _CharT, class _InputIterator>