depends on the heat, if it's not hot, I'd think 2 bottles is enough + a small 8-10oz or something in your back pocket. If the sun it out and gonna be in the 80+ range, I'll be wearing the camel bak + the 2 bottles. If you do that, drink from the camelbak first, so by the time you get to the 2nd half of the climbs, you will have less water weight on your back.

Just bring everything, weather changes so fast in the mountains.