Brasso is very good on polishing nitro and acrylic finishes, I'd imagine it would be good on poly as well, as it is just mainly a cutting compound. Silvo is a slightly coarser polishing liquid than Brasso, so if you have any lying around, you could always try that first followed by Brasso.

However, you don't want to leave a puddle of it on the finish, as it can dissolve the finish and leave a rough patch. I discovered this the hard way after unknowingly leaving an acrylic finished guitar sitting on a small puddle of Brasso. But applying it via a cloth and then rubbing away and cleaning off is fine.