How to split folders of a git repo into separate branches?

I've been charged with converting our TFS repo over to git (via this thingy). The TFS repo is set up thus:

$/root
    /branch1
    /branch2
    /branch3

...etc, with the TFS branches appearing in th开发者_如何学JAVAe imported git repo as folders. Is there a way of splitting each branchX off as a branch of the git repo, making the contents the new root?

There's a tool called git-subtree doing exactly that.