D.N.
Have you tried just letting him put himself back to sleep? When I first transitioned my daughter to her own room, I used to give her 30 min. to cry it out. The first few times it took all the strength I had not to go to her, but after a few nights, the time it took her to get back to sleep lessened and lessened. Now, on occasion, when she does wake up, she cries for less than a minute and goes right back to sleep.
Good luck and I hope this helps.