Résumé
We prove that the automorphism group of every infinitely ended finitely generated group is acylindrically hyperbolic. In particular Aut(Fn) is acylindrically hyperbolic for every n > 2. More generally, if G is a group which is not virtually cyclic, and hyperbolic relative to a finite collection P of finitely generated proper subgroups, then Aut(G,P) is acylindrically hyperbolic. As a consequence, a free-by-cyclic group F-n X-phi Zis acylindrically hyperbolic if and only if phi has infinite order in Out(F-n).