Am I supposed to run BFG on the mirrored repo or the original?

First 3 steps with BFG:

1. Download BFG using the following command in terminal: brew install bfg

2. Clone a fresh copy of your repo, using the --mirror flag.

   git clone --mirror git://example.com/some-big-repo.git
   

   The mirror flag allows you to make a full copy of the Git database without actually copying down the files of the repo.

3. bfg --the-options-you-want the-mirror-repo-you-just-cloned.git

Adapted from this manual by an IBM engineer. Don't cd into the repo as it says on step 3, otherwise you'll get an error "the-mirror-repo-you-just-cloned.git is not a valid Git repository."