diff --git a/include/llvm/ADT/SmallVector.h b/include/llvm/ADT/SmallVector.h
index 2d79a029d01..18c8619bf93 100644
--- a/include/llvm/ADT/SmallVector.h
+++ b/include/llvm/ADT/SmallVector.h
@@ -59,7 +59,7 @@ protected:
   // number of union instances for the space, which guarantee maximal alignment.
   struct U {
 #ifdef __GNUC__
-    char X __attribute__((aligned));
+    char X __attribute__((aligned(8)));
 #else
     union {
       double D;