# Do this the first time: $ git remote add -f -t master --no-tags gitgit https://github.com/git/git.git $ git subtree add --squash --prefix=third_party/git gitgit/master # In future, you can merge in additional changes as follows: $ git subtree pull --squash --prefix=third_party/git gitgit/master # And you can push changes back upstream as follows: $ git subtree push --prefix=third_party/git gitgit/master # Or possibly (not sure what the difference is): $ git subtree push --squash --prefix=third_party/git gitgit/master