Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td	(revision 218519)
+++ include/clang/Basic/DiagnosticGroups.td	(working copy)
@@ -146,6 +146,8 @@
 
 def CXX11Narrowing : DiagGroup<"c++11-narrowing">;
 
+def CXX11WarnOverrideMethod : DiagGroup<"warn-missing-override-on-overriding-method">;
+
 // Original name of this warning in Clang
 def : DiagGroup<"c++0x-narrowing", [CXX11Narrowing]>;
 
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td	(revision 218519)
+++ include/clang/Basic/DiagnosticSemaKinds.td	(working copy)
@@ -1688,6 +1688,9 @@
   "%select{function|functions}1">;
 def err_function_marked_override_not_overriding : Error<
   "%0 marked 'override' but does not override any member functions">;
+def warn_function_marked_not_override_overriding : Warning <
+  "%0 is not marked 'override' but overrides a member functions">,
+  InGroup<CXX11WarnOverrideMethod>;
 def err_class_marked_final_used_as_base : Error<
   "base %0 is marked '%select{final|sealed}1'">;
 def warn_abstract_final_class : Warning<
Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h	(revision 218519)
+++ include/clang/Sema/Sema.h	(working copy)
@@ -5084,6 +5084,10 @@
 
   /// CheckOverrideControl - Check C++11 override control semantics.
   void CheckOverrideControl(NamedDecl *D);
+    
+  /// DiagnoseAbsenseOfOverrideControl - Diagnose if override control was
+  /// not used in the; otherwise, overriding method.
+  void DiagnoseAbsenseOfOverrideControl(NamedDecl *D);
 
   /// CheckForFunctionMarkedFinal - Checks whether a virtual member function
   /// overrides a virtual member function marked 'final', according to
Index: lib/Sema/SemaDeclCXX.cpp
===================================================================
--- lib/Sema/SemaDeclCXX.cpp	(revision 218519)
+++ lib/Sema/SemaDeclCXX.cpp	(working copy)
@@ -1895,6 +1895,27 @@
       << MD->getDeclName();
 }
 
+void Sema::DiagnoseAbsenseOfOverrideControl(NamedDecl *D) {
+  if (D->isInvalidDecl())
+    return;
+  CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D);
+  if (!MD || MD->isImplicit())
+    return;
+
+  bool HasOverriddenMethods =
+    MD->begin_overridden_methods() != MD->end_overridden_methods();
+  if (HasOverriddenMethods) {
+    Diag(MD->getLocation(), diag::warn_function_marked_not_override_overriding)
+      << MD->getDeclName();
+    for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(),
+         E = MD->end_overridden_methods(); I != E; ++I) {
+      const CXXMethodDecl *OMD = *I;
+      Diag(OMD->getLocation(), diag::note_overridden_virtual_function);
+      break;
+    }
+  }
+}
+
 /// CheckIfOverriddenFunctionIsMarkedFinal - Checks whether a virtual member
 /// function overrides a virtual member function marked 'final', according to
 /// C++11 [class.virtual]p4.
@@ -4650,13 +4671,15 @@
     }
   }
 
+  bool HasMethodWithOverrideControl = false;
   if (!Record->isDependentType()) {
     for (auto *M : Record->methods()) {
       // See if a method overloads virtual methods in a base
       // class without overriding any.
       if (!M->isStatic())
         DiagnoseHiddenVirtualMethods(M);
-
+      if (M->hasAttr<OverrideAttr>())
+        HasMethodWithOverrideControl = true;
       // Check whether the explicitly-defaulted special members are valid.
       if (!M->isInvalidDecl() && M->isExplicitlyDefaulted())
         CheckExplicitlyDefaultedSpecialMember(M);
@@ -4675,6 +4698,13 @@
     }
   }
 
+  if (HasMethodWithOverrideControl) {
+    // At list one method has the 'override' control declared.
+    // Diagnose all other overridden methods which do not have 'override' specified on them.
+    for (auto *M : Record->methods())
+      if (!M->hasAttr<OverrideAttr>())
+        DiagnoseAbsenseOfOverrideControl(M);
+  }
   // C++11 [dcl.constexpr]p8: A constexpr specifier for a non-static member
   // function that is not a constructor declares that member function to be
   // const. [...] The class of which that function is a member shall be
Index: test/CXX/class.derived/class.virtual/p3-0x.cpp
===================================================================
--- test/CXX/class.derived/class.virtual/p3-0x.cpp	(revision 218519)
+++ test/CXX/class.derived/class.virtual/p3-0x.cpp	(working copy)
@@ -61,7 +61,7 @@
 namespace PR13499 {
   struct X {
     virtual void f();
-    virtual void h();
+    virtual void h(); // expected-note 2 {{overridden virtual function is here}}
   };
   template<typename T> struct A : X {
     void f() override;
@@ -83,7 +83,7 @@
   template<typename...T> struct E : X {
     void f(T...) override;
     void g(T...) override; // expected-error {{only virtual member functions can be marked 'override'}}
-    void h(T...) final;
+    void h(T...) final; // expected-warning {{'h' is not marked 'override' but overrides a member functions}}
     void i(T...) final; // expected-error {{only virtual member functions can be marked 'final'}}
   };
   // FIXME: Diagnose these in the template definition, not in the instantiation.
@@ -91,13 +91,13 @@
 
   template<typename T> struct Y : T {
     void f() override;
-    void h() final;
+    void h() final; // expected-warning {{'h' is not marked 'override' but overrides a member functions}}
   };
   template<typename T> struct Z : T {
     void g() override; // expected-error {{only virtual member functions can be marked 'override'}}
     void i() final; // expected-error {{only virtual member functions can be marked 'final'}}
   };
-  Y<X> y;
+  Y<X> y; // expected-note {{in instantiation of}}
   Z<X> z; // expected-note {{in instantiation of}}
 }
 
Index: test/FixIt/fixit-cxx0x.cpp
===================================================================
--- test/FixIt/fixit-cxx0x.cpp	(revision 218519)
+++ test/FixIt/fixit-cxx0x.cpp	(working copy)
@@ -24,7 +24,7 @@
   int o;
 
   struct Base {
-    virtual void f2(), f3();
+    virtual void f2(), f3(); // expected-note {{overridden virtual function is here}}
   };
   struct MemberDeclarator : Base {
     int k : 4,
@@ -33,7 +33,7 @@
     char c, // expected-error {{expected ';' at end of declaration}}
     typedef void F(), // expected-error {{expected ';' at end of declaration}}
     F f1,
-      f2 final,
+      f2 final, // expected-warning {{'f2' is not marked 'override' but overrides a member functions}}
       f3 override, // expected-error {{expected ';' at end of declaration}}
   };
 }
Index: test/Parser/MicrosoftExtensions.cpp
===================================================================
--- test/Parser/MicrosoftExtensions.cpp	(revision 218519)
+++ test/Parser/MicrosoftExtensions.cpp	(working copy)
@@ -208,12 +208,12 @@
 
 __interface MicrosoftInterface;
 __interface MicrosoftInterface {
-   void foo1() = 0;
+   void foo1() = 0; // expected-note {{overridden virtual function is here}}
    virtual void foo2() = 0;
 };
 
 __interface MicrosoftDerivedInterface : public MicrosoftInterface {
-  void foo1();
+  void foo1(); // expected-warning {{'foo1' is not marked 'override' but overrides a member functions}}
   void foo2() override;
   void foo3();
 };
Index: test/Parser/cxx0x-decl.cpp
===================================================================
--- test/Parser/cxx0x-decl.cpp	(revision 218519)
+++ test/Parser/cxx0x-decl.cpp	(working copy)
@@ -83,13 +83,13 @@
 
 namespace FinalOverride {
   struct Base {
-    virtual void *f();
+    virtual void *f(); // expected-note {{overridden virtual function is here}}
     virtual void *g();
     virtual void *h();
     virtual void *i();
   };
   struct Derived : Base {
-    virtual auto f() -> void *final;
+    virtual auto f() -> void *final; // expected-warning {{'f' is not marked 'override' but overrides a member functions}}
     virtual auto g() -> void *override;
     virtual auto h() -> void *final override;
     virtual auto i() -> void *override final;
Index: test/Parser/cxx0x-in-cxx98.cpp
===================================================================
--- test/Parser/cxx0x-in-cxx98.cpp	(revision 218519)
+++ test/Parser/cxx0x-in-cxx98.cpp	(working copy)
@@ -10,11 +10,12 @@
 
 struct B {
   virtual void f();
-  virtual void g();
+  virtual void g(); // expected-note {{overridden virtual function is here}}
 };
 struct D final : B { // expected-warning {{'final' keyword is a C++11 extension}}
   virtual void f() override; // expected-warning {{'override' keyword is a C++11 extension}}
-  virtual void g() final; // expected-warning {{'final' keyword is a C++11 extension}}
+  virtual void g() final; // expected-warning {{'final' keyword is a C++11 extension}} \
+			  // expected-warning {{'g' is not marked 'override' but overrides a member functions}}
 };
 
 void NewBracedInitList() {
Index: test/SemaCXX/MicrosoftExtensions.cpp
===================================================================
--- test/SemaCXX/MicrosoftExtensions.cpp	(revision 218519)
+++ test/SemaCXX/MicrosoftExtensions.cpp	(working copy)
@@ -372,14 +372,14 @@
 
   // expected-note@+2 {{overridden virtual function is here}}
   // expected-warning@+1 {{'sealed' keyword is a Microsoft extension}}
-  virtual void SealedFunction() sealed;
+  virtual void SealedFunction() sealed; // expected-note {{overridden virtual function is here}}
 };
 
 // expected-note@+2 {{'SealedType' declared here}}
 // expected-warning@+1 {{'sealed' keyword is a Microsoft extension}}
 struct SealedType sealed : SomeBase {
   // expected-error@+1 {{declaration of 'SealedFunction' overrides a 'sealed' function}}
-  virtual void SealedFunction();
+  virtual void SealedFunction(); // expected-warning {{'SealedFunction' is not marked 'override' but overrides a member functions}}
 
   // expected-warning@+1 {{'override' keyword is a C++11 extension}}
   virtual void OverrideMe() override;
Index: test/SemaCXX/attr-gnu.cpp
===================================================================
--- test/SemaCXX/attr-gnu.cpp	(revision 218519)
+++ test/SemaCXX/attr-gnu.cpp	(working copy)
@@ -15,14 +15,15 @@
 namespace {
 class B {
 public:
-  virtual void test() {}
+  virtual void test() {} // expected-note {{overridden virtual function is here}}
   virtual void test2() {}
   virtual void test3() {}
 };
 
 class D : public B {
 public:
-  void test() __attribute__((deprecated)) final {} // expected-warning {{GCC does not allow an attribute in this position on a function declaration}}
+  void test() __attribute__((deprecated)) final {} // expected-warning {{GCC does not allow an attribute in this position on a function declaration}} \
+						   // expected-warning {{'test' is not marked 'override' but overrides a member functions}}
   void test2() [[]] override {} // Ok
   void test3() __attribute__((cf_unknown_transfer)) override {} // Ok, not known to GCC.
 };
Index: test/SemaCXX/cxx11-warn-missing-override.cpp
===================================================================
--- test/SemaCXX/cxx11-warn-missing-override.cpp	(revision 0)
+++ test/SemaCXX/cxx11-warn-missing-override.cpp	(working copy)
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -fsyntax-only -Wwarn-missing-override-on-overriding-method -verify -std=c++11 %s
+struct A
+{
+    virtual void foo();
+    virtual void bar(); // expected-note {{overridden virtual function is here}}
+    virtual void gorf() {}
+    virtual void g() = 0; // expected-note {{overridden virtual function is here}}
+};
+ 
+struct B : A
+{
+    void foo() override;
+    void bar(); // expected-warning {{'bar' is not marked 'override' but overrides a member functions}}
+};
+
+struct C : B 
+{
+    virtual void g() = 0;  // expected-warning {{'g' is not marked 'override' but overrides a member functions}}
+    virtual void gorf() override {}
+};
+
Index: test/SemaCXX/cxx98-compat.cpp
===================================================================
--- test/SemaCXX/cxx98-compat.cpp	(revision 218519)
+++ test/SemaCXX/cxx98-compat.cpp	(working copy)
@@ -120,11 +120,12 @@
 
 struct OverrideControlBase {
   virtual void f();
-  virtual void g();
+  virtual void g(); // expected-note {{overridden virtual function is here}}
 };
 struct OverrideControl final : OverrideControlBase { // expected-warning {{'final' keyword is incompatible with C++98}}
   virtual void f() override; // expected-warning {{'override' keyword is incompatible with C++98}}
-  virtual void g() final; // expected-warning {{'final' keyword is incompatible with C++98}}
+  virtual void g() final; // expected-warning {{'final' keyword is incompatible with C++98}} \
+			  // expected-warning {{'g' is not marked 'override' but overrides a member functions}}
 };
 
 using AliasDecl = int; // expected-warning {{alias declarations are incompatible with C++98}}
Index: test/SemaCXX/ms-interface.cpp
===================================================================
--- test/SemaCXX/ms-interface.cpp	(revision 218519)
+++ test/SemaCXX/ms-interface.cpp	(working copy)
@@ -12,7 +12,7 @@
   operator int();
   // expected-error@+1 {{nested class I1::(anonymous) is not permitted within an interface type}}
   struct { int a; };
-  void fn2() {
+  void fn2() { // expected-note {{overridden virtual function is here}}
     struct A { }; // should be ignored: not a nested class
   }
 protected: // expected-error {{interface types cannot specify 'protected' access}}
@@ -44,7 +44,7 @@
 __interface I4 : I1, I2 {
   void fn1() const override;
   // expected-error@+1 {{'final' keyword not permitted with interface types}}
-  void fn2() final;
+  void fn2() final; // expected-warning {{'fn2' is not marked 'override' but overrides a member functions}}
 };
 
 // expected-error@+1 {{interface type cannot inherit from non-public 'interface I1'}}