Pax's New Name -- It's the Pitts!

Angelina Jolie has filed a petition in L.A. County Superior Court to change the name of her latest adopted child from Pax Thien Jolie to Pax Thien Jolie-Pitt.

In papers filed April 16 and obtained today by TMZ, Angelina -- the sole adoptive parent of Pax -- is requesting the change so it will reflect the last name of her partner, Brad Pitt, and so it is the same as that of her other three children.

Angelina adopted the three-and-a-half-year-old little boy from an orphanage in Vietnam last March.