diff --git a/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 8600c9ebf79..c3259254f8b 100644
--- a/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -626,10 +626,14 @@ bool MemCpyOpt::performCallSlotOptzn(Instruction *cpy,
       return false;
 
     Type *StructTy = cast<PointerType>(A->getType())->getElementType();
-    // If StructTy is an opaque type, it should have at least <cpyLen> bytes,
-    // as implified by the copy-instruction.
-    uint64_t destSize = StructTy->isSized() ?
-                        TD->getTypeAllocSize(StructTy) : cpyLen;
+    if (!StructTy->isSized()) {
+      // The call may never return and hence the copy-instruction may never
+      // be executed, and therefore it's not safe to say "the destination
+      // has at least <cpyLen> bytes, as implied by the copy-instruction",
+      return false;
+    }
+
+    uint64_t destSize = TD->getTypeAllocSize(StructTy);
     if (destSize < srcSize)
       return false;
   } else {
diff --git a/test/Transforms/MemCpyOpt/memcpy.ll b/test/Transforms/MemCpyOpt/memcpy.ll
index fa768712ec9..148623a6ce7 100644
--- a/test/Transforms/MemCpyOpt/memcpy.ll
+++ b/test/Transforms/MemCpyOpt/memcpy.ll
@@ -185,28 +185,6 @@ define void @test10(%opaque* noalias nocapture sret %x, i32 %y) {
   ret void
 }
 
-; Test11 is similar to test10 except that the instruction "store i32 %y, i32* %a"
-; before the call-site is deleted. MemCopyOpt is able to optimize this snippet into
-;
-;  %x1 = bitcast %opaque* %x to i32*
-;  call void @foo(i32* noalias nocapture %x1)
-;  ret void
-; 
-
-define void @test11(%opaque* noalias nocapture sret %x, i32 %y) {
-; CHECK: test11
-; CHECK: %x1 = bitcast %opaque* %x to i32*
-; CHECK: call void @foo(i32* noalias nocapture %x1)
-; CHECK: ret void
-
-  %a = alloca i32, align 4
-  call void @foo(i32* noalias nocapture %a)
-  %c = load i32* %a
-  %d = bitcast %opaque* %x to i32*
-  store i32 %c, i32* %d
-  ret void
-}
-
 declare void @f1(%struct.big* sret)
 declare void @f2(%struct.big*)