How do I check if a type is a subtype OR the type of an object?

To check if a type is a subclass of another type in C#, it’s easy:

typeof (SubClass).IsSubclassOf(typeof (BaseClass)); // returns true

However, this will fail:

typeof (BaseClass).IsSubclassOf(typeof (BaseClass)); // returns false

Is there any way to check whether a type is either a subclass OR of the base class itself, without using an OR operator or using an extension method?