I have a working copy of the project, without any source control meta data. Now, I\'d like to do the equivalent of git-clone into this folder, and keep my local changes.
Lots of answers already to do it the way that the OP asked. But it worth noting that doing it the opposite way around is far simpler:
git clone repo-url tmp/ cp -R working/ tmp/
You now have the desired target state - fresh clone + local-changes.