O’Reilly graduated from Menlo (School) in the heart of Silicon Valley in 2003 and also attended the University of Southern California in Los Angeles for one year. She reportedly dated fellow actor James Franco between 2006 and 2011. Cast as Dewey Dell Bundren in the film version of William Faulkner’s 1930 classic novel, As I Lay Dying, O’Reilly was directed by former boyfriend James Franco. In an October 2013 interview with The Hollywood Reporter, she gave high praise to Franco’s directorial debut. In a November 2013 interview with Popsugar.com, O’Reilly confirmed the rumor that she will again be teaming up with James Franco in a movie adaptation of another William Faulkner book, The Sound and the Fury, in 2014.