In February 2014, Metallica began recording a new song at their HQ studio in San Rafael, California, with the working title "X-Dust", planning to premiere it at a March 16, 2014, show in Bogotá, Colombia. They finished it in March and premiered it at the show with the official song title "Lords of Summer". The band re-recorded the song in May and June 2015 for their tenth studio album, Hardwired... to Self-Destruct (2016), including it with the deluxe edition of the album. It is over a minute shorter in length than the demo and first pass versions.
The band released the song digitally through the iTunes Store on March 19, 2014, in its demo form. They eventually released the song in a more refined state, dubbed the "First Pass Version", digitally in June. Later that year, they gave the song a physical release for Record Store Day Black Friday as a 12-inch single, with a live version of the song recorded in Rome being used as the B-side. The single was limited to 4,000 copies. A remix of the song by The Glitch Mob was released on May 13, 2015, through YouTube.