Feature request: git cp

I am splitting a large source file into three smaller ones (mp3.c into mad.c, lame.c and twolame.c) and would like the history to track the relevant lines in each file, like "git mv" does, but I only seem able to do this with one file by "git mv"ing it and copying that to the other as a new file.

So what I'd like is "git cp" that is like "git mv" but where blame for both the resulting files goes back the original one, if that's possible and unless there's a way to achieve the same effect that I haven't figured out.

A fairly rare thing to wish to do, but may be useful in this case.

    M