Pitbull, Christina Aguilera, Macklemore and Ryan Lewis, Selena Gomez, the Band Perry and Kacey Musgraves have joined the star-packed performance lineup for the Billboard Music Awards, which already includes Prince, Justin Bieber, Taylor Swift, Bruno Mars and Miguel. The show will air live on Sunday, May 19, from the MGM Grand Garden Arena in Las Vegas on ABC, with "30 Rock" alum Tracy Morgan set to host and Don Mischer to produce.