diff --git a/llvm/include/llvm/IR/DerivedTypes.h b/llvm/include/llvm/IR/DerivedTypes.h
--- a/llvm/include/llvm/IR/DerivedTypes.h
+++ b/llvm/include/llvm/IR/DerivedTypes.h
@@ -531,6 +531,8 @@
   }
 };
 
+bool Type::isVectorTy() const { return isa<VectorType>(this); }
+
 /// Class to represent pointers.
 class PointerType : public Type {
   explicit PointerType(Type *ElType, unsigned AddrSpace);
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
@@ -223,7 +223,7 @@
   bool isPtrOrPtrVectorTy() const { return getScalarType()->isPointerTy(); }
 
   /// True if this is an instance of VectorType.
-  bool isVectorTy() const { return getTypeID() == VectorTyID; }
+  inline bool isVectorTy() const;
 
   /// 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