She is wearing Louis Vuitton Spring Summer 2015 on the cover that was photographed by Kerry Hallihan. (source)
Click here to view last year cover featuring Katie Holmes, here to view 2013 covers featuring Rihanna, here for 2012 cover with Mary-Kate and Ashley Olsen, here to view 2011 covers featuring Gwen Stefani and here for 2010 covers featuring Chloe Sevigny.