Create ragdoll out of gameobjects that are not touching

I have a "human" ragdoll that I created using six gameobjects: a cube for the head, torso, right and left arms, and right and left legs. It looks like this:

That image has bad lighting, but hopefully you are able to see that there is a gap between the limbs and the torso. That is because I like that style. However, the problem is that this will not act as a ragdoll. Instead, it will just fall apart. Obviously, I want to be able to have my characters not fall apart. How would I be able to keep these limbs together?