Following history of a copied file from another indirect branch

It has become a necessity to copy a file from one long-lived branch to another. It is not possible to merge the branches at this time.

I would like to have 'git gui blame' follow the copy back through its original history, but I don't believe Git has metadata for storing this. Something along the lines of a 'followparent' in the commit object, for instance, would allow the revision walking code to wander the history down an alternate line.

By comparison, integrates work at a file level in Perforce. That means I can integrate a file from one branch to another, and parentage is stored such that I can follow the file back through its history.

Are there any facilities to do this now?

Thanks!

Josh