Index: lib/Sema/SemaTemplate.cpp
===================================================================
--- lib/Sema/SemaTemplate.cpp
+++ lib/Sema/SemaTemplate.cpp
@@ -7017,6 +7017,16 @@
     return true;
   }
 
+  // C++ [temp]p6:
+  //   A template, a template explicit specialization, and a class template
+  //   partial specialization shall not have C linkage.
+  if (S.CurContext->isExternCContext()) {
+    S.Diag(Loc, diag::err_template_linkage);
+    if (const LinkageSpecDecl *LSD = S.CurContext->getExternCContext())
+      S.Diag(LSD->getExternLoc(), diag::note_extern_c_begins_here);
+    return true;
+  }
+
   // C++ [temp.expl.spec]p2:
   //   An explicit specialization shall be declared in the namespace
   //   of which the template is a member, or, for member templates, in
Index: test/SemaTemplate/class-template-spec.cpp
===================================================================
--- test/SemaTemplate/class-template-spec.cpp
+++ test/SemaTemplate/class-template-spec.cpp
@@ -235,3 +235,9 @@
   > struct S;
   template<typename T> struct S<T> {}; // expected-error {{non-type template argument specializes a template parameter with dependent type 'T'}}
 }
+
+template<typename T> struct C {};
+extern "C" { // expected-note 2{{extern "C" language linkage specification begins here}}
+  template<typename T> struct C<T*> {}; // expected-error{{templates must have C++ linkage}}
+  template<> struct C<int> {}; // expected-error{{templates must have C++ linkage}}
+}
Index: test/SemaTemplate/function-template-specialization.cpp
===================================================================
--- test/SemaTemplate/function-template-specialization.cpp
+++ test/SemaTemplate/function-template-specialization.cpp
@@ -56,3 +56,8 @@
   template<>
   static void Bar(const long& input) {}  // expected-error{{explicit specialization of 'Bar' in class scope}}
 };
+
+template<typename T> void f3(T) {}
+extern "C" { // expected-note {{extern "C" language linkage specification begins here}}
+  template<> void f3(int) {} // expected-error{{templates must have C++ linkage}}
+}