diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index b3f2067ff68c..95288acb86c9 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -254,9 +254,6 @@ def err_missing_comma_before_ellipsis : Error<
   "C requires a comma prior to the ellipsis in a variadic function type">;
 def err_unexpected_typedef_ident : Error<
   "unexpected type name %0: expected identifier">;
-def ext_gnu_decltype : Extension<
-  "'__decltype' type specifier is a GNU extension">,
-  InGroup<GNU>, DefaultIgnore;
 def warn_cxx98_compat_decltype : Warning<
   "'decltype' type specifier is incompatible with C++98">,
   InGroup<CXX98Compat>, DefaultIgnore;
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 5468700bc925..d798281f40f8 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -653,8 +653,8 @@ SourceLocation Parser::ParseDecltypeSpecifier(DeclSpec &DS) {
       return EndLoc;
     }
   } else {
-    Diag(Tok, Tok.getIdentifierInfo()->isStr("decltype")
-           ? diag::warn_cxx98_compat_decltype : diag::ext_gnu_decltype);
+    if (Tok.getIdentifierInfo()->isStr("decltype"))
+      Diag(Tok, diag::warn_cxx98_compat_decltype);
 
     ConsumeToken();
 
diff --git a/clang/test/SemaCXX/decltype-98.cpp b/clang/test/SemaCXX/decltype-98.cpp
index 44d5896c53ea..db52565e6c74 100644
--- a/clang/test/SemaCXX/decltype-98.cpp
+++ b/clang/test/SemaCXX/decltype-98.cpp
@@ -1,3 +1,3 @@
-// RUN: %clang_cc1 -std=c++98 -fsyntax-only -verify %s -Wgnu
+// RUN: %clang_cc1 -std=c++98 -fsyntax-only -verify %s
 extern int x;
-__decltype(1) x = 3; // expected-warning {{is a GNU extension}}
+__decltype(1) x = 3;