Credit: Brooks/

Well, that was fast! The late Elvis Presley's granddaughter Riley Keough has locked in her hunka-hunka burnin' love!

After about six months of dating, Lisa Marie Presley's model-actress daughter, 22, is engaged to Alex Pettyfer, a source confirms to Us Weekly.

After connecting as costars on the upcoming male stripper flick Magic Mike, Keough and the British actor, 21, were first photographed smooching last October. And on Monday, the twosome grabbed lunch at Le Petit Four in L.A. --with Keough sporting an engagement ring.

Pettyfer, who strips down alongside Channing Tatum, Joe Manganiello and Matthew Bomer in Steven Soderbergh's Magic Mike, has previously dated actresses Emma Roberts and Dianna Agron.

Keough's exes include Ryan Cabrera and Jonah Hill.