Index: libcxx/include/regex
===================================================================
--- libcxx/include/regex
+++ libcxx/include/regex
@@ -2837,6 +2837,8 @@
         __parse_awk_escape(_ForwardIterator __first, _ForwardIterator __last,
                           basic_string<_CharT>* __str = nullptr);
 
+    bool __test_back_ref(_CharT c);
+
     _LIBCPP_INLINE_VISIBILITY
     void __push_l_anchor();
     void __push_r_anchor();
@@ -3408,18 +3410,8 @@
     if (__first != __last)
     {
         _ForwardIterator __temp = _VSTD::next(__first);
-        if (__temp != __last)
-        {
-            if (*__first == '\\')
-            {
-                int __val = __traits_.value(*__temp, 10);
-                if (__val >= 1 && __val <= 9)
-                {
-                    __push_back_ref(__val);
-                    __first = ++__temp;
-                }
-            }
-        }
+        if (__temp != __last && *__first == '\\' && __test_back_ref(*__temp))
+            __first = ++__temp;
     }
     return __first;
 }
@@ -3547,6 +3539,8 @@
                 default:
                     if (__get_grammar(__flags_) == awk)
                         __first = __parse_awk_escape(++__first, __last);
+                    else if(__test_back_ref(*__temp))
+                        __first = ++__temp;
                     break;
                 }
             }
@@ -4661,6 +4655,20 @@
 }
 
 template <class _CharT, class _Traits>
+bool
+basic_regex<_CharT, _Traits>::__test_back_ref(_CharT c)
+{
+    unsigned __val = __traits_.value(c, 10);
+    if (__val >= 1 && __val <= 9)
+    {
+        __push_back_ref(__val);
+        return true;
+    }
+
+    return false;
+}
+
+template <class _CharT, class _Traits>
 void
 basic_regex<_CharT, _Traits>::__push_loop(size_t __min, size_t __max,
         __owns_one_state<_CharT>* __s, size_t __mexp_begin, size_t __mexp_end,
Index: libcxx/test/std/re/re.alg/re.alg.match/extended.pass.cpp
===================================================================
--- libcxx/test/std/re/re.alg/re.alg.match/extended.pass.cpp
+++ libcxx/test/std/re/re.alg/re.alg.match/extended.pass.cpp
@@ -432,6 +432,24 @@
     {
         std::cmatch m;
         const char s[] = "-ab,ab-";
+        assert(std::regex_match(s, m, std::regex("-(.*),\\1-", std::regex_constants::extended)));
+        assert(m.size() == 2);
+        assert(!m.prefix().matched);
+        assert(m.prefix().first == s);
+        assert(m.prefix().second == m[0].first);
+        assert(!m.suffix().matched);
+        assert(m.suffix().first == m[0].second);
+        assert(m.suffix().second == m[0].second);
+        assert(m.length(0) >= 0 && static_cast<size_t>(m.length(0)) == std::char_traits<char>::length(s));
+        assert(m.position(0) == 0);
+        assert(m.str(0) == s);
+        assert(m.length(1) == 2);
+        assert(m.position(1) == 1);
+        assert(m.str(1) == "ab");
+    }
+    {
+        std::cmatch m;
+        const char s[] = "-ab,ab-";
         assert(std::regex_match(s, m, std::regex("-.*,.*-", std::regex_constants::extended)));
         assert(m.size() == 1);
         assert(!m.prefix().matched);
@@ -1100,6 +1118,24 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"-ab,ab-";
+        assert(std::regex_match(s, m, std::wregex(L"-(.*),\\1-", std::regex_constants::extended)));
+        assert(m.size() == 2);
+        assert(!m.prefix().matched);
+        assert(m.prefix().first == s);
+        assert(m.prefix().second == m[0].first);
+        assert(!m.suffix().matched);
+        assert(m.suffix().first == m[0].second);
+        assert(m.suffix().second == m[0].second);
+        assert(m.length(0) >= 0 && static_cast<size_t>(m.length(0)) == std::char_traits<wchar_t>::length(s));
+        assert(m.position(0) == 0);
+        assert(m.str(0) == s);
+        assert(m.length(1) == 2);
+        assert(m.position(1) == 1);
+        assert(m.str(1) == L"ab");
+    }
+    {
+        std::wcmatch m;
+        const wchar_t s[] = L"-ab,ab-";
         assert(std::regex_match(s, m, std::wregex(L"-.*,.*-", std::regex_constants::extended)));
         assert(m.size() == 1);
         assert(!m.prefix().matched);
Index: libcxx/test/std/re/re.alg/re.alg.search/extended.pass.cpp
===================================================================
--- libcxx/test/std/re/re.alg/re.alg.search/extended.pass.cpp
+++ libcxx/test/std/re/re.alg/re.alg.search/extended.pass.cpp
@@ -495,6 +495,24 @@
     {
         std::cmatch m;
         const char s[] = "-ab,ab-";
+        assert(std::regex_search(s, m, std::regex("-(.*),\\1-", std::regex_constants::extended)));
+        assert(m.size() == 2);
+        assert(!m.prefix().matched);
+        assert(m.prefix().first == s);
+        assert(m.prefix().second == m[0].first);
+        assert(!m.suffix().matched);
+        assert(m.suffix().first == m[0].second);
+        assert(m.suffix().second == m[0].second);
+        assert(m.length(0) >= 0 && static_cast<size_t>(m.length(0)) == std::char_traits<char>::length(s));
+        assert(m.position(0) == 0);
+        assert(m.str(0) == s);
+        assert(m.length(1) == 2);
+        assert(m.position(1) == 1);
+        assert(m.str(1) == "ab");
+    }
+    {
+        std::cmatch m;
+        const char s[] = "-ab,ab-";
         assert(std::regex_search(s, m, std::regex("-.*,.*-", std::regex_constants::extended)));
         assert(m.size() == 1);
         assert(!m.prefix().matched);
@@ -1253,6 +1271,24 @@
     {
         std::wcmatch m;
         const wchar_t s[] = L"-ab,ab-";
+        assert(std::regex_search(s, m, std::wregex(L"-(.*),\\1-", std::regex_constants::extended)));
+        assert(m.size() == 2);
+        assert(!m.prefix().matched);
+        assert(m.prefix().first == s);
+        assert(m.prefix().second == m[0].first);
+        assert(!m.suffix().matched);
+        assert(m.suffix().first == m[0].second);
+        assert(m.suffix().second == m[0].second);
+        assert(m.length(0) >= 0 && static_cast<size_t>(m.length(0)) == std::char_traits<wchar_t>::length(s));
+        assert(m.position(0) == 0);
+        assert(m.str(0) == s);
+        assert(m.length(1) == 2);
+        assert(m.position(1) == 1);
+        assert(m.str(1) == L"ab");
+    }
+    {
+        std::wcmatch m;
+        const wchar_t s[] = L"-ab,ab-";
         assert(std::regex_search(s, m, std::wregex(L"-.*,.*-", std::regex_constants::extended)));
         assert(m.size() == 1);
         assert(!m.prefix().matched);