diff --git a/clang/lib/Sema/SemaObjCProperty.cpp b/clang/lib/Sema/SemaObjCProperty.cpp
index 56aa4480fbe6..34c702076593 100644
--- a/clang/lib/Sema/SemaObjCProperty.cpp
+++ b/clang/lib/Sema/SemaObjCProperty.cpp
@@ -1249,10 +1249,20 @@ ObjCPropertyDecl *Sema::LookupPropertyDecl(const ObjCContainerDecl *CDecl,
   return 0;
 }
 
+static IdentifierInfo * getDefaultSynthIvarName(ObjCPropertyDecl *Prop,
+                                                ASTContext &Ctx) {
+  llvm::SmallString<128> ivarName;
+  {
+    llvm::raw_svector_ostream os(ivarName);
+    os << '_' << Prop->getIdentifier()->getName();
+  }
+  return &Ctx.Idents.get(ivarName.str());
+}
+
 /// DefaultSynthesizeProperties - This routine 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) {
   
   llvm::DenseMap<IdentifierInfo *, ObjCPropertyDecl*> PropMap;
   CollectClassPropertyImplementations(IDecl, PropMap);
@@ -1289,7 +1299,8 @@ void Sema::DefaultSynthesizeProperties (Scope *S, ObjCImplDecl* IMPDecl,
     // to help users.
     ActOnPropertyImplDecl(S, SourceLocation(), SourceLocation(),
                           true,
-                          Prop->getIdentifier(), Prop->getIdentifier(),
+                          /* property = */ Prop->getIdentifier(),
+                          /* ivar = */ getDefaultSynthIvarName(Prop, Context),
                           SourceLocation());
   }
 }
diff --git a/clang/test/Index/complete-synthesized.m b/clang/test/Index/complete-synthesized.m
index 4d2d80b84598..e6e49fb778d1 100644
--- a/clang/test/Index/complete-synthesized.m
+++ b/clang/test/Index/complete-synthesized.m
@@ -27,7 +27,7 @@
 @dynamic prop3;
 
 - (short)method2 {
-  return prop4;
+  return _prop4;
 }
 
 - (short)method3 {
@@ -43,4 +43,4 @@
 // CHECK: ObjCIvarDecl:{ResultType float}{TypedText _prop2} (35)
 // CHECK-NOT: prop2
 // CHECK-NOT: prop3
-// CHECK: ObjCIvarDecl:{ResultType double}{TypedText prop4} (37)
+// CHECK: ObjCIvarDecl:{ResultType double}{TypedText _prop4} (37)
diff --git a/clang/test/SemaObjC/default-synthesize-1.m b/clang/test/SemaObjC/default-synthesize-1.m
index 3a27a1d9c7c8..9774de6e3bb2 100644
--- a/clang/test/SemaObjC/default-synthesize-1.m
+++ b/clang/test/SemaObjC/default-synthesize-1.m
@@ -25,12 +25,12 @@
 //@synthesize howMany, what;
 
 - (int) howMany {
-    return howMany;
+    return _howMany;
 }
 // - (void) setHowMany: (int) value
 
 - (NSString*) what {
-    return what;
+    return _what;
 }
 // - (void) setWhat: (NSString*) value    
 @end
@@ -46,14 +46,14 @@
 
 // - (int) howMany
 - (void) setHowMany: (int) value {
-    howMany = value;
+    _howMany = value;
 }
 
 // - (NSString*) what
 - (void) setWhat: (NSString*) value {
-    if (what != value) {
-        [what release];
-        what = [value retain];
+    if (_what != value) {
+        [_what release];
+        _what = [value retain];
     }
 }
 @end
diff --git a/clang/test/SemaObjC/default-synthesize-2.m b/clang/test/SemaObjC/default-synthesize-2.m
index d402348c2581..92a147d14c9f 100644
--- a/clang/test/SemaObjC/default-synthesize-2.m
+++ b/clang/test/SemaObjC/default-synthesize-2.m
@@ -16,7 +16,7 @@
 // @synthesize name, rank, serialNumber;
 // default synthesis allows direct access to property ivars.
 - (id)init {
-        name = rank = serialNumber = 0;
+        _name = _rank = _serialNumber = 0;
 	return self;
 }
 
@@ -41,7 +41,7 @@
 // Test3
 @interface Test3 
 { 
-  id _uid; 
+  id uid; 
 } 
 @property (readwrite, assign) id uid; 
 @end
@@ -50,8 +50,8 @@
 // Oops, forgot to write @synthesize! will be default synthesized
 - (void) myMethod { 
    self.uid = 0; // Use of the “setter” 
-   _uid = 0; // Use of the wrong instance variable
-   uid = 0; // Use of the property instance variable
+   uid = 0; // Use of the wrong instance variable
+   _uid = 0; // Use of the property instance variable
 } 
 @end
 
@@ -65,7 +65,7 @@
 // default synthesize property named 'var'
 @implementation Test4 
 - (id) myMethod {
-  return self->var;  //  compiles because 'var' is synthesized by default
+  return self->_var;  //  compiles because 'var' is synthesized by default
 }
 @end
 
@@ -80,7 +80,7 @@
 @implementation Test5 
 - (id) myMethod {
   Test5 *foo = 0; 
-  return foo->var; // OK
+  return foo->_var; // OK
 } 
 @end
 
@@ -100,19 +100,17 @@
 @synthesize var = _var; 
 @end
 
-int* object;
+int* _object;
 
-@interface Test7 {
-id _object;
-} 
+@interface Test7
 @property (readwrite, assign) id object; 
 @end
 
-// With default synthesis, 'object' is be the synthesized ivar not the global
+// With default synthesis, '_object' is be the synthesized ivar not the global
 // 'int*' object. So no error.
 @implementation Test7 
 - (id) myMethod {
-  return object;
+  return _object;
 } 
 @end
 
diff --git a/clang/test/SemaObjC/direct-synthesized-ivar-access.m b/clang/test/SemaObjC/direct-synthesized-ivar-access.m
index d9be872b4556..b1a470ab2e5c 100644
--- a/clang/test/SemaObjC/direct-synthesized-ivar-access.m
+++ b/clang/test/SemaObjC/direct-synthesized-ivar-access.m
@@ -10,6 +10,6 @@
 @end
 
 @implementation I
-- (int) Meth { return IVAR; }
+- (int) Meth { return _IVAR; }
 - (int) OK { return self.IVAR; }
 @end
diff --git a/clang/test/SemaObjC/synth-provisional-ivars.m b/clang/test/SemaObjC/synth-provisional-ivars.m
index 8a743220416e..752a577a011d 100644
--- a/clang/test/SemaObjC/synth-provisional-ivars.m
+++ b/clang/test/SemaObjC/synth-provisional-ivars.m
@@ -18,7 +18,7 @@ int bar;
 @end
 
 @implementation I
-- (int) Meth { return PROP; }
+- (int) Meth { return _PROP; }
 
 @dynamic PROP1;
 - (int) Meth1 { return PROP1; }  // expected-error {{use of undeclared identifier 'PROP1'}}
@@ -30,12 +30,12 @@ int bar;
 @synthesize PROP3=IVAR;
 
 - (int) Meth4 { return PROP4; }
-@synthesize PROP4=PROP4;
+@synthesize PROP4=PROP4; // expected-note 4 {{'PROP4' declared here}}
 
 - (int) Meth5 { return bar; }
 @synthesize bar = _bar;
 
-- (int) Meth6 { return bar1; }
+- (int) Meth6 { return _bar1; }
 
 @end
 
diff --git a/clang/test/SemaObjC/synthesized-ivar.m b/clang/test/SemaObjC/synthesized-ivar.m
index 4786d808fa2f..12e7df1f5347 100644
--- a/clang/test/SemaObjC/synthesized-ivar.m
+++ b/clang/test/SemaObjC/synthesized-ivar.m
@@ -31,8 +31,8 @@ int f0(I *a) { return a->IP; } // expected-error {{instance variable 'IP' is pri
 
 @implementation I1
 - (int) Meth {
-   PROP_INMAIN = 1;
-   PROP_INCLASSEXT = 2;
+   _PROP_INMAIN = 1;
+   _PROP_INCLASSEXT = 2;
    protected_ivar = 1;	// OK
    return private_ivar; // OK
 }
@@ -45,8 +45,8 @@ int f0(I *a) { return a->IP; } // expected-error {{instance variable 'IP' is pri
 @implementation DER
 - (int) Meth {
    protected_ivar = 1;	// OK
-   PROP_INMAIN = 1; // expected-error {{instance variable 'PROP_INMAIN' is private}}
-   PROP_INCLASSEXT = 2; // expected-error {{instance variable 'PROP_INCLASSEXT' is private}}
+   _PROP_INMAIN = 1; // expected-error {{instance variable '_PROP_INMAIN' is private}}
+   _PROP_INCLASSEXT = 2; // expected-error {{instance variable '_PROP_INCLASSEXT' is private}}
    return private_ivar; // expected-error {{instance variable 'private_ivar' is private}}
 }
 @end