diff --git a/lib/CodeGen/TargetInfo.cpp b/lib/CodeGen/TargetInfo.cpp
index 0c070a1..7c850af 100644
--- a/lib/CodeGen/TargetInfo.cpp
+++ b/lib/CodeGen/TargetInfo.cpp
@@ -1228,6 +1228,13 @@
 
     const RecordDecl *RD = RT->getDecl();
 
+    // The only case a 256-bit wide vector could be used is when the struct
+    // contains a single 256-bit element. Since Lo and Hi logic isn't extended
+    // to work for sizes wider than 128, early check and fallback to memory.
+    RecordDecl::field_iterator FirstElt = RD->field_begin();
+    if (Size > 128 && getContext().getTypeSize(FirstElt->getType()) != 256)
+      return;
+
     // Assume variable sized types are passed in memory.
     if (RD->hasFlexibleArrayMember())
       return;
@@ -1263,7 +1270,7 @@
 
     // Classify the fields one at a time, merging the results.
     unsigned idx = 0;
-    for (RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
+    for (RecordDecl::field_iterator i = FirstElt, e = RD->field_end();
            i != e; ++i, ++idx) {
       uint64_t Offset = OffsetBase + Layout.getFieldOffset(idx);
       bool BitField = i->isBitField();