Git doesn't show how many commits ahead of origin I am, and I want it to

git branch --set-upstream local origin/remote

local and remote are the names of your local resp. remote branches.

In Git version 1.8 and later, it's even easier. Make sure you're on the local branch, and then:

git branch --set-upstream-to origin/remote

I found that there's a way to make this behavior the default:

git config --global branch.autosetupmerge always

Despite the name, this doesn't force you to always merge branches; you can still rebase if you want to.

It will ensure that any time you create a new branch, you'll automatically be able to see how many commits different it is from the branch it was created from.