diff --git a/lib/Sema/SemaObjCProperty.cpp b/lib/Sema/SemaObjCProperty.cpp
index 41ed6c6..030fdaa 100644
--- a/lib/Sema/SemaObjCProperty.cpp
+++ b/lib/Sema/SemaObjCProperty.cpp
@@ -93,6 +93,11 @@
   ObjCPropertyDecl *PDecl =
     ObjCPropertyDecl::Create(Context, DC, FD.D.getIdentifierLoc(),
                              PropertyId, AtLoc, T);
+  if (Attributes & ObjCDeclSpec::DQ_PR_readonly)
+    PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_readonly);
+  if (Attributes & ObjCDeclSpec::DQ_PR_readwrite)
+    PDecl->setPropertyAttributes(ObjCPropertyDecl::OBJC_PR_readwrite);
+
   DC->addDecl(PDecl);
 
   // We need to look in the @interface to see if the @property was
diff --git a/test/SemaObjC/property-in-class-extension.m b/test/SemaObjC/property-in-class-extension.m
new file mode 100644
index 0000000..3f252d0
--- /dev/null
+++ b/test/SemaObjC/property-in-class-extension.m
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1  -fsyntax-only -verify %s
+// rdar: // 7766184
+
+@interface Foo @end
+
+@interface Foo ()
+  @property (readonly) int bar;
+@end
+
+void FUNC () {
+    Foo *foo;
+    foo.bar = 0; // expected-error {{assigning to property with 'readonly' attribute not allowed}}
+}
+
+