Index: test/Lexer/has_feature_cxx0x.cpp
===================================================================
--- test/Lexer/has_feature_cxx0x.cpp	(revision 220262)
+++ test/Lexer/has_feature_cxx0x.cpp	(working copy)
@@ -407,6 +407,16 @@
 // CHECK-11: no_decltype_auto
 // CHECK-NO-11: no_decltype_auto
 
+#if __has_feature(cxx_digit_separators)
+int has_digit_separators();
+#else
+int no_digit_separators();
+#endif
+
+// CHECK-1Y: has_digit_separators
+// CHECK-11: no_digit_separators
+// CHECK-NO-11: no_digit_separators
+
 #if __has_feature(cxx_generic_lambdas)
 int has_generic_lambdas();
 #else
Index: lib/Lex/PPMacroExpansion.cpp
===================================================================
--- lib/Lex/PPMacroExpansion.cpp	(revision 220262)
+++ lib/Lex/PPMacroExpansion.cpp	(working copy)
@@ -957,6 +957,7 @@
            .Case("cxx_binary_literals", LangOpts.CPlusPlus14)
            .Case("cxx_contextual_conversions", LangOpts.CPlusPlus14)
            .Case("cxx_decltype_auto", LangOpts.CPlusPlus14)
+           .Case("cxx_digit_separators", LangOpts.CPlusPlus14)
            .Case("cxx_generic_lambdas", LangOpts.CPlusPlus14)
            .Case("cxx_init_captures", LangOpts.CPlusPlus14)
            .Case("cxx_relaxed_constexpr", LangOpts.CPlusPlus14)