The UFC is in the process of booking several marquee bouts for its summer schedule.
UFC co-owner Lorenzo Fertitta broke the news early Friday morning via his personal Twitter account.
In addition, Fertitta confirmed the UFC is working to pair former heavyweight champions Frank Mir and Cain Velasquez on an undisclosed date, and light heavyweights Forrest Griffin and Tito Ortiz are expected to meet a third time.
According to UFC officials, none of the bouts has been formally signed.
Dos Santos (14-1) claimed the UFC heavyweight belt last November with a 64-second KO win over Velasquez (9-1). The 27-year-old Brazilian has won eight straight fights in the promotion, finishing all but two.
He'll meet another dangerous striker in Overeem (36-11), barring any legal setback the Dutch fighter faces with a misdemeanor battery charge stemming from an incident earlier this year in Las Vegas.
The UFC has not officially announced the May 26 event in Las Vegas, which is expected to take place at the MGM Grand Garden Arena.
Mir (16-5) is currently riding a three-fight win streak, including a first-round submission victory over Antonio Rodrigo Nogueira at UFC 140 in December. For Velasquez, it will mark his first return to the cage since losing the belt.
Ortiz (16-10-1) is coming off a first-round TKO loss to Antonio Rogerio Nogueira in December and has lost six of his past eight fights. Ortiz, 37, has one fight remaining on his current deal with the UFC and has speculated it will be his last.
Per his request, Ortiz will finish his trilogy with Griffin (18-7). The two have split prior meetings -- in 2006 and 2009 -- both of which ended in split decisions.
Brett Okamoto covers mixed martial arts for ESPN.com.