diff --git a/llvm/include/llvm/IR/Type.h b/llvm/include/llvm/IR/Type.h
--- a/llvm/include/llvm/IR/Type.h
+++ b/llvm/include/llvm/IR/Type.h
@@ -34,6 +34,7 @@
 class PointerType;
 class raw_ostream;
 class StringRef;
+class VectorType;
 
 /// The instances of the Type class are immutable: once they are created,
 /// they are never changed.  Also note that only one instance of a particular
@@ -227,7 +228,7 @@
   bool isPtrOrPtrVectorTy() const { return getScalarType()->isPointerTy(); }
 
   /// True if this is an instance of VectorType.
-  bool isVectorTy() const { return getTypeID() == VectorTyID; }
+  bool isVectorTy() const { return isa<VectorType>(this); }
 
   /// Return true if this type could be converted with a lossless BitCast to
   /// type 'Ty'. For example, i8* to i32*. BitCasts are valid for types of the