Thanks @Duncaen, that did the trick.
Last time I tried that method I neglected to specify the -H param which is why it didn't work for me. Works now though, and I can install the packages I built in the glibc chroot
EDIT: I take it back, it wasn't the -H that fixed it. It was that one of the packages I was trying to build earlier was broken, and I just didn't build that package this time. This still works for building glibc packages though