Patrick, I am 5′ 11″ and 185 also. I have a Large long sleeve that fits snug which I think you want. The sleeves and torso length are just fine. It is about 6 years old, I assume the sizes are the same. I am old. If you are muscular up top, you might find a large confining in the biceps and chest.
As a side note, I never thought to wear it in warmer weather as suggested here. I wore it yesterday at 65F and took it off after about 30 minutes of mild hiking. Far too hot even with a very thin loose fitting side vented Rail Riders button down shirt over it.