diff --git a/include/clang/Basic/Builtins.def b/include/clang/Basic/Builtins.def
index f45ca44..d12a04d 100644
--- a/include/clang/Basic/Builtins.def
+++ b/include/clang/Basic/Builtins.def
@@ -35,6 +35,7 @@
 //  A -> "reference" to __builtin_va_list
 //  V -> Vector, following num elements and a base type.
 //  X -> _Complex, followed by the base type.
+//  Y -> ptrdiff_t
 //  P -> FILE
 //  J -> jmp_buf
 //  SJ -> sigjmp_buf
@@ -690,8 +691,7 @@
 // id objc_assign_weak(id value, id *location)
 LIBBUILTIN(objc_assign_weak, "GGG*", "f", "/objc/objc-auto.h", OBJC_LANG)
 // id objc_assign_ivar(id value, id dest, ptrdiff_t offset)
-// FIXME. Darwin has ptrdiff_t typedef'ed to int.
-LIBBUILTIN(objc_assign_ivar, "GGGi", "f", "/objc/objc-auto.h", OBJC_LANG)
+LIBBUILTIN(objc_assign_ivar, "GGGY", "f", "/objc/objc-auto.h", OBJC_LANG)
 // id objc_assign_global(id val, id *dest)
 LIBBUILTIN(objc_assign_global, "GGG*", "f", "/objc/objc-auto.h", OBJC_LANG)
 // id objc_assign_strongCast(id val, id *dest
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 1b2c5cf..75a573e 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -6140,7 +6140,11 @@
     assert(!RequiresICE && "Can't require complex ICE");
     Type = Context.getComplexType(ElementType);
     break;
-  }      
+  }  
+  case 'Y' : {
+    Type = Context.getPointerDiffType();
+    break;
+  }
   case 'P':
     Type = Context.getFILEType();
     if (Type.isNull()) {
diff --git a/test/SemaObjC/builtin_objc_assign_ivar.m b/test/SemaObjC/builtin_objc_assign_ivar.m
new file mode 100644
index 0000000..5839bf4
--- /dev/null
+++ b/test/SemaObjC/builtin_objc_assign_ivar.m
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -x objective-c %s -fsyntax-only -verify
+// rdar://9362887
+
+typedef __typeof__(((int*)0)-((int*)0)) ptrdiff_t;
+extern id objc_assign_ivar(id value, id dest, ptrdiff_t offset);
+