http://admission.universityofcalifornia.edu/counselors/exam-credit/ap-credits/index.html indicates that high enough AP test scores give 4 or 8 quarter units (or 2.7 or 5.3 semester units for UCB and UCM).
Note, however, that duplicative content does not get double credit. For example, someone with both calculus AB and BC scores gets at most 8 quarter units.