Upstream Tracking

This page is no longer actively maintained to find the common upstream revision for a branch, use git merge-base.

As an example:

> git fetch upstream && git merge-base feature/reflect upstream/master
...
559845f8fe53fabb22f9a392e8d34761df250c72

If you do not have the upstream remote, you can add it via:

git remote add upstream git@github.com:llvm/llvm-project.git