diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index dbdfb1ebef3c..ef39bd260dcb 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -2418,6 +2418,12 @@ public:
             llvm::DenseMap<IdentifierInfo *, ObjCPropertyDecl*>& PropMap,
             llvm::DenseMap<IdentifierInfo *, ObjCPropertyDecl*>& SuperPropMap);
   
+  /// IvarBacksCurrentMethodAccessor - This routine returns 'true' if 'IV' is
+  /// an ivar synthesized for 'Method' and 'Method' is a property accessor
+  /// declared in class 'IFace'.
+  bool IvarBacksCurrentMethodAccessor(ObjCInterfaceDecl *IFace,
+                                      ObjCMethodDecl *Method, ObjCIvarDecl *IV);
+  
   /// Called by ActOnProperty to handle \@property declarations in
   /// class extensions.
   ObjCPropertyDecl *HandlePropertyInClassExtension(Scope *S,
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index b3ba2dc4ae92..0ed460cc5e28 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -2042,7 +2042,8 @@ Sema::LookupInObjCMethod(LookupResult &Lookup, Scope *S,
       MarkAnyDeclReferenced(Loc, IV, true);
       
       ObjCMethodFamily MF = CurMethod->getMethodFamily();
-      if (MF != OMF_init && MF != OMF_dealloc && MF != OMF_finalize)
+      if (MF != OMF_init && MF != OMF_dealloc && MF != OMF_finalize &&
+          !IvarBacksCurrentMethodAccessor(IFace, CurMethod, IV))
         Diag(Loc, diag::warn_direct_ivar_access) << IV->getDeclName();
 
       ObjCIvarRefExpr *Result = new (Context) ObjCIvarRefExpr(IV, IV->getType(),
diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp
index f1f810402026..16f4a43bd77f 100644
--- a/clang/lib/Sema/SemaExprMember.cpp
+++ b/clang/lib/Sema/SemaExprMember.cpp
@@ -1259,7 +1259,8 @@ Sema::LookupMemberExpr(LookupResult &R, ExprResult &BaseExpr,
       if (ObjCMethodDecl *MD = getCurMethodDecl()) {
         ObjCMethodFamily MF = MD->getMethodFamily();
         warn = (MF != OMF_init && MF != OMF_dealloc && 
-                MF != OMF_finalize);
+                MF != OMF_finalize &&
+                !IvarBacksCurrentMethodAccessor(IDecl, MD, IV));
       }
       if (warn)
         Diag(MemberLoc, diag::warn_direct_ivar_access) << IV->getDeclName();
diff --git a/clang/lib/Sema/SemaObjCProperty.cpp b/clang/lib/Sema/SemaObjCProperty.cpp
index 1fe88a26ab0e..e238b7ea20d4 100644
--- a/clang/lib/Sema/SemaObjCProperty.cpp
+++ b/clang/lib/Sema/SemaObjCProperty.cpp
@@ -1541,6 +1541,33 @@ static void CollectSuperClassPropertyImplementations(ObjCInterfaceDecl *CDecl,
   }
 }
 
+/// IvarBacksCurrentMethodAccessor - This routine returns 'true' if 'IV' is
+/// an ivar synthesized for 'Method' and 'Method' is a property accessor
+/// declared in class 'IFace'.
+bool
+Sema::IvarBacksCurrentMethodAccessor(ObjCInterfaceDecl *IFace,
+                                     ObjCMethodDecl *Method, ObjCIvarDecl *IV) {
+  if (!IV->getSynthesize())
+    return false;
+  ObjCMethodDecl *IMD = IFace->lookupMethod(Method->getSelector(),
+                                            Method->isInstanceMethod());
+  if (!IMD || !IMD->isPropertyAccessor())
+    return false;
+  
+  // look up a property declaration whose one of its accessors is implemented
+  // by this method.
+  for (ObjCContainerDecl::prop_iterator P = IFace->prop_begin(),
+       E = IFace->prop_end(); P != E; ++P) {
+    ObjCPropertyDecl *property = *P;
+    if ((property->getGetterName() == IMD->getSelector() ||
+         property->getSetterName() == IMD->getSelector()) &&
+        (property->getPropertyIvarDecl() == IV))
+      return true;
+  }
+  return false;
+}
+
+
 /// \brief Default synthesizes all properties which must be synthesized
 /// in class's \@implementation.
 void Sema::DefaultSynthesizeProperties(Scope *S, ObjCImplDecl* IMPDecl,
diff --git a/clang/test/SemaObjC/warn-direct-ivar-access.m b/clang/test/SemaObjC/warn-direct-ivar-access.m
index 4f242e6b338c..283a00faee8c 100644
--- a/clang/test/SemaObjC/warn-direct-ivar-access.m
+++ b/clang/test/SemaObjC/warn-direct-ivar-access.m
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1  -fsyntax-only -fobjc-arc -fobjc-runtime-has-weak  -Wdirect-ivar-access -verify -Wno-objc-root-class %s
+// RUN: %clang_cc1  -fsyntax-only -fobjc-arc -fobjc-runtime-has-weak  -fobjc-default-synthesize-properties -Wdirect-ivar-access -verify -Wno-objc-root-class %s
 // rdar://6505197
 
 __attribute__((objc_root_class)) @interface MyObject {
@@ -54,3 +54,25 @@ id Test32(__weak ITest32 *x) {
            : (*x).ivar;  // expected-error {{dereferencing a __weak pointer is not allowed}}
 }
 
+// rdar://13142820
+@protocol PROTOCOL
+@property (copy, nonatomic) id property_in_protocol;
+@end
+
+__attribute__((objc_root_class)) @interface INTF <PROTOCOL>
+@property (copy, nonatomic) id foo;
+- (id) foo;
+@end
+
+@interface INTF()
+@property (copy, nonatomic) id foo1;
+- (id) foo1;
+@end
+
+@implementation INTF
+- (id) foo { return _foo; }
+- (id) property_in_protocol { return _property_in_protocol; } // expected-warning {{instance variable '_property_in_protocol' is being directly accessed}}
+- (id) foo1 { return _foo1; }
+@synthesize property_in_protocol = _property_in_protocol;
+@end
+