diff --git a/clang/lib/Parse/AttributeList.cpp b/clang/lib/Parse/AttributeList.cpp
index 3cd74d57f56db7755ff39938ae319042ab56f29e..0ab67107fadf29a0d79a958b2ab54d5d146fbe33 100644
--- a/clang/lib/Parse/AttributeList.cpp
+++ b/clang/lib/Parse/AttributeList.cpp
@@ -105,6 +105,7 @@ AttributeList::Kind AttributeList::getKind(const IdentifierInfo *Name) {
     .Case("overloadable", AT_overloadable)
     .Case("address_space", AT_address_space)
     .Case("always_inline", AT_always_inline)
+    .Case("returns_twice", IgnoredAttribute)
     .Case("vec_type_hint", IgnoredAttribute)
     .Case("objc_exception", AT_objc_exception)
     .Case("ext_vector_type", AT_ext_vector_type)