Index: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1029,6 +1029,8 @@
   "auto property synthesis will not synthesize property %0"
   " declared in protocol %1">,
   InGroup<DiagGroup<"objc-protocol-property-synthesis">>;
+def note_add_synthesize_directive : Note<
+  "add a '@synthesize' directive">;
 def warn_no_autosynthesis_shared_ivar_property : Warning <
   "auto property synthesis will not synthesize property "
   "%0 because it cannot share an ivar with another synthesized property">,
Index: cfe/trunk/include/clang/Sema/Sema.h
===================================================================
--- cfe/trunk/include/clang/Sema/Sema.h
+++ cfe/trunk/include/clang/Sema/Sema.h
@@ -3358,9 +3358,10 @@
 
   /// DefaultSynthesizeProperties - This routine default synthesizes all
   /// properties which must be synthesized in the class's \@implementation.
-  void DefaultSynthesizeProperties (Scope *S, ObjCImplDecl* IMPDecl,
-                                    ObjCInterfaceDecl *IDecl);
-  void DefaultSynthesizeProperties(Scope *S, Decl *D);
+  void DefaultSynthesizeProperties(Scope *S, ObjCImplDecl *IMPDecl,
+                                   ObjCInterfaceDecl *IDecl,
+                                   SourceLocation AtEnd);
+  void DefaultSynthesizeProperties(Scope *S, Decl *D, SourceLocation AtEnd);
 
   /// IvarBacksCurrentMethodAccessor - This routine returns 'true' if 'IV' is
   /// an ivar synthesized for 'Method' and 'Method' is a property accessor
Index: cfe/trunk/lib/Parse/ParseObjc.cpp
===================================================================
--- cfe/trunk/lib/Parse/ParseObjc.cpp
+++ cfe/trunk/lib/Parse/ParseObjc.cpp
@@ -2255,7 +2255,7 @@
 
 void Parser::ObjCImplParsingDataRAII::finish(SourceRange AtEnd) {
   assert(!Finished);
-  P.Actions.DefaultSynthesizeProperties(P.getCurScope(), Dcl);
+  P.Actions.DefaultSynthesizeProperties(P.getCurScope(), Dcl, AtEnd.getBegin());
   for (size_t i = 0; i < LateParsedObjCMethods.size(); ++i)
     P.ParseLexedObjCMethodDefs(*LateParsedObjCMethods[i], 
                                true/*Methods*/);
Index: cfe/trunk/lib/Sema/SemaObjCProperty.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaObjCProperty.cpp
+++ cfe/trunk/lib/Sema/SemaObjCProperty.cpp
@@ -1676,8 +1676,9 @@
 
 /// \brief Default synthesizes all properties which must be synthesized
 /// in class's \@implementation.
-void Sema::DefaultSynthesizeProperties(Scope *S, ObjCImplDecl* IMPDecl,
-                                       ObjCInterfaceDecl *IDecl) {
+void Sema::DefaultSynthesizeProperties(Scope *S, ObjCImplDecl *IMPDecl,
+                                       ObjCInterfaceDecl *IDecl,
+                                       SourceLocation AtEnd) {
   ObjCInterfaceDecl::PropertyMap PropMap;
   ObjCInterfaceDecl::PropertyDeclOrder PropertyOrder;
   IDecl->collectPropertiesToImplement(PropMap, PropertyOrder);
@@ -1725,6 +1726,10 @@
              diag::warn_auto_synthesizing_protocol_property)
           << Prop << Proto;
         Diag(Prop->getLocation(), diag::note_property_declare);
+        std::string FixIt =
+            (Twine("@synthesize ") + Prop->getName() + ";\n\n").str();
+        Diag(AtEnd, diag::note_add_synthesize_directive)
+            << FixItHint::CreateInsertion(AtEnd, FixIt);
       }
       continue;
     }
@@ -1764,7 +1769,8 @@
   }
 }
 
-void Sema::DefaultSynthesizeProperties(Scope *S, Decl *D) {
+void Sema::DefaultSynthesizeProperties(Scope *S, Decl *D,
+                                       SourceLocation AtEnd) {
   if (!LangOpts.ObjCDefaultSynthProperties || LangOpts.ObjCRuntime.isFragile())
     return;
   ObjCImplementationDecl *IC=dyn_cast_or_null<ObjCImplementationDecl>(D);
@@ -1772,7 +1778,7 @@
     return;
   if (ObjCInterfaceDecl* IDecl = IC->getClassInterface())
     if (!IDecl->isObjCRequiresPropertyDefs())
-      DefaultSynthesizeProperties(S, IC, IDecl);
+      DefaultSynthesizeProperties(S, IC, IDecl, AtEnd);
 }
 
 static void DiagnoseUnimplementedAccessor(
Index: cfe/trunk/test/FixIt/fixit-add-synthesize-to-property.m
===================================================================
--- cfe/trunk/test/FixIt/fixit-add-synthesize-to-property.m
+++ cfe/trunk/test/FixIt/fixit-add-synthesize-to-property.m
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+
+@protocol P1
+
+@property int prop;
+
+@end
+
+@interface I <P1>
+
+@end
+
+@implementation I
+@end // CHECK: fix-it:{{.*}}:{[[@LINE]]:1-[[@LINE]]:1}:"@synthesize prop;\n\n"
Index: cfe/trunk/test/SemaObjC/default-synthesize-3.m
===================================================================
--- cfe/trunk/test/SemaObjC/default-synthesize-3.m
+++ cfe/trunk/test/SemaObjC/default-synthesize-3.m
@@ -173,13 +173,13 @@
 @end
 
 @implementation Okay // expected-warning {{auto property synthesis will not synthesize property 'muahahaha' declared in protocol 'Fooing'}} expected-warning {{auto property synthesis will not synthesize property 'hoho' declared in protocol 'SubFooling'}}
-@end
+@end // expected-note 2 {{add a '@synthesize' directive}}
 
 @interface Fail : FooObject
 @end
 
 @implementation Fail // expected-warning {{auto property synthesis will not synthesize property 'muahahaha' declared in protocol 'Fooing'}} expected-warning {{auto property synthesis will not synthesize property 'hoho' declared in protocol 'SubFooling'}}
-@end
+@end // expected-note 2 {{add a '@synthesize' directive}}
 
 // rdar://16089191
 @class NSURL;
Index: cfe/trunk/test/SemaObjC/default-synthesize.m
===================================================================
--- cfe/trunk/test/SemaObjC/default-synthesize.m
+++ cfe/trunk/test/SemaObjC/default-synthesize.m
@@ -137,7 +137,7 @@
 @end
  
 @implementation MyClass // expected-warning {{auto property synthesis will not synthesize property 'requiredString' declared in protocol 'MyProtocol'}}
-@end
+@end // expected-note {{add a '@synthesize' directive}}
 
 // rdar://18152478
 @protocol NSObject @end
Index: cfe/trunk/test/SemaObjC/forward-protocol-incomplete-impl-warn.m
===================================================================
--- cfe/trunk/test/SemaObjC/forward-protocol-incomplete-impl-warn.m
+++ cfe/trunk/test/SemaObjC/forward-protocol-incomplete-impl-warn.m
@@ -17,4 +17,4 @@
 
 @implementation IBImageCatalogDocument // expected-warning {{auto property synthesis will not synthesize property 'Prop' declared in protocol 'DVTInvalidation'}} \
 				       // expected-warning {{method 'invalidate' in protocol 'DVTInvalidation' not implemented}}
-@end
+@end // expected-note {{add a '@synthesize' directive}}