How to get my humanoid models base position in the scene view into a T-Pose

I imported my model into unity, but when i set up the humanoid rig the base position turned into this

Imgur: The magic of the Internet [1] (my model on the right)

I would instead like him to look like the base guy on the right.
Anyone know why this is happening?

On the right is the pose that occurs when you are in the muscle setup panel. Go to the Bone setup panel and Force T-Pose from the dropdown at the bottom.