diff --git a/clang/lib/Headers/unwind.h b/clang/lib/Headers/unwind.h
index c5ad04863f48..22414a4e46d0 100644
--- a/clang/lib/Headers/unwind.h
+++ b/clang/lib/Headers/unwind.h
@@ -149,7 +149,7 @@ struct _Unwind_Control_Block {
     uint32_t reserved1;
   } pr_cache;
   long long int : 0; /* force alignment of next item to 8-byte boundary */
-} __attribute__((__aligned__));
+} __attribute__((__aligned__(8)));
 #else
 struct _Unwind_Exception {
   _Unwind_Exception_Class exception_class;