diff --git a/lib/IR/Instructions.cpp b/lib/IR/Instructions.cpp
index 8c4eeafdf84..7136923ecb4 100644
--- a/lib/IR/Instructions.cpp
+++ b/lib/IR/Instructions.cpp
@@ -2864,10 +2864,6 @@ CastInst::castIsValid(Instruction::CastOps op, Value *S, Type *DstTy) {
   // Check for type sanity on the arguments
   Type *SrcTy = S->getType();
 
-  // If this is a cast to the same type then it's trivially true.
-  if (SrcTy == DstTy)
-    return true;
-
   if (!SrcTy->isFirstClassType() || !DstTy->isFirstClassType() ||
       SrcTy->isAggregateType() || DstTy->isAggregateType())
     return false;
diff --git a/test/Assembler/invalid_cast4.ll b/test/Assembler/invalid_cast4.ll
new file mode 100644
index 00000000000..7056f840035
--- /dev/null
+++ b/test/Assembler/invalid_cast4.ll
@@ -0,0 +1,4 @@
+; RUN: not llvm-as < %s 2>&1 | FileCheck %s
+
+; CHECK: invalid cast opcode for cast from 'i64' to 'i64'
+global i64* inttoptr (i64 0 to i64)