Originally Posted by aktchi

Three hours should be plenty, but...

You'd be arriving in T5 (International). Then immigration, wait for luggage, customs. Your departing flight (if AA) is likely to be from T3.

The most important thing is to re-check you bags in T5 itself at the airline counter immediately after Customs. If you see large doors open and find people waiting to receive passengers, turn back! It would be a major inconvenience to transport your luggage to T3.