diff --git a/llvm/lib/Analysis/MemoryBuiltins.cpp b/llvm/lib/Analysis/MemoryBuiltins.cpp
--- a/llvm/lib/Analysis/MemoryBuiltins.cpp
+++ b/llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -336,9 +336,12 @@
     return V->getOperand(FnData->AlignParam);
   }
   unsigned AllocAlignParam;
+  const Function *F = V->getCalledFunction();
   if (V->getAttributes().hasAttrSomewhere(Attribute::AllocAlign,
-                                          &AllocAlignParam)) {
-    return V->getOperand(AllocAlignParam-1);
+                                          &AllocAlignParam) ||
+      (F && F->getAttributes().hasAttrSomewhere(Attribute::AllocAlign,
+                                                &AllocAlignParam))) {
+    return V->getOperand(AllocAlignParam - 1);
   }
   return nullptr;
 }