An NxN rotation matrix has N (N-1) / 2 embedded angles. The rotation of a unit right-hand-rule coordinate system into the orientation of R requires these many rotations. In your case there are three angles.
No, Matlab does not have such a built in function. I, too, rolled my own. Take care with the arc-tan's you'll need, certainly use the atan(y, x) form so that you don't lose a 180 deg rotation.