Automagical dependency determination?

I've got a 10 year old codebase that currently carries around just under 3 gigs of "support" libraries. We know that the majority of these aren't actually used, but which ones?

In the magical place in my head where my wishes exist I imagine a tool that can statically analyze my .java/.cpp/.f files and tell me exactly which libraries I'm depending on. I'd settle for even just which jars we depend on. Anyone have any thoughts on such a tool, or even a procedure by which we can pare down this baggage?