If you have natural shade, I would recommend you site your coop/run there, because it can make a big difference. The first coop/run I built was open sided, but I put it someplace in our yard where it gets afternoon sun. Big mistake. Our most recent coop/run is in the shadiest part of the yard, and the temp differential between the two was running over 20 degrees. 105 is bad enough; 125 is ridiculous.
I ran a mister on the worst days, and that really helped bring down the temps in that area a good 5-10 degrees. I did bring my bantams indoors at night for a while because the night time temps were dropping down only into the high 80's, and I thought the flock needed to get some relief from heat stress.
I would also recommend you pick heat tolerant breeds if you can. Our d'Uccles start panting around 90 degrees, but our Serama/Old English scarcely seem to get bothered even at 100.