Recursively copy only new or changed files

Question

I'm sure this must have been asked and answered before, but I just can't find it right now...
I have a Visual Studio post-build action that currently does a recursive copy (using xcopy) of an output folder to a different folder. This takes longer than I like and I'd like to only copy newly created and newer (changed) files each time (which xcopy doesn't seem to support).

I cannot depend on any not-installed-by-default tool since the solution is used by different developers on different machines.
What would a superuser do?

Answer 1

A superuser would use xcopy /m.

Actually, no, a superuser would use rsync. But since you can only use built-in tools, there you are.

Answer 2

Robocopy is ideal for this, and it's installed by default on Vista and newer. If you're on a domain, you could also push it out with gp if needed. If you're using XP, then go with xcopy, and Ignacio says.