The derailer is a Shimano XT M750 SGS, which is supposed to handle a 34T sprocket, which is what my largest one is. But still, the pulley and the sprocket rub against each other. The tips of the teeth just touch and make a rattling noise.
I always thought the angle adjustment screw was supposed to take care of this problem, but the only thing that screw does is changing the limit for the entire derailer arm's swing. It does absolutely nothing to increase or decrease the distance between pulley and sprocket.
This isn't a major problem, because the worst thing that will happen is my upper pulley wearing out faster (since it's plastic), but the noise is annoying, so I'd like it fixed, if possible.