He is expected to travel with the tour party to Sydney this weekend and is likely to make his home debut in the Emirates Cup on July 29 or July 30.
Manager Arsène Wenger said: “We are very happy to have Alexandre join our group. He has shown over a number of years that he can score goals and that he is a very efficient finisher. As well, he has very interesting technical qualities and a strong character. So he is a guy who is a great addition for us, and someone who will help us challenge at the top level this season.”