When Phase 1 of the Marvel Cinematic Universe came to a close with The Avengers, the post credit scene revealing Thanos made it very clear that one of the biggest threats imaginable would be taking on the heroes in the future. After multiple teases and appearances that amount to mere cameos, Thanos will be fully realized in Avengers: Infinity War. Throughout this movie in particular, it is believed that audiences will get to witness Thanos traveling throughout the galaxy collecting the Infinity Stones he needs to power the Infinity Gauntlet. So far, four Infinity Stones have been revealed with only the Time Stone and Soul Stone remaining to be revealed.
Given the properties that will be released prior to Infinity War, it has been heavily speculated that Doctor Strange will be responsible for bringing one of the remaining stones to the big screen. Many people have theorized that the Eye of Agamotto is a housing the Time Stone within it, similarly to Loki's Staff housing the mind stone before. While this is nothing more than speculation at this point, Marvel Studios head Kevin Feige is certainly teasing the possibility.
In an interview with EW regarding the costume of Doctor Strange, both Feige and director Scott Derrickson were asked about the power and design of the Eye of Agamotto. Neither have confirmed that an Infinity Stone is partially responsible for the source of Strange's powers, but Feige did state that it could “screw around with time.” If there is an Infinity Stone inside the Eye, Derrickson did not feel it was necessary to drastically change the design:
It was so cool — we knew we didn’t have to improve greatly upon what was in the comics for it to be interesting for a modern audience.
It would certainly make sense for Doctor Strange to use an Infinity Stone as it would further connect the film to major events in the larger MCU. While it does sound like a cool way to connect the films, it would also leave Strange in the position of having to lose the Eye in his next appearance. That would be unfortunate for fans of the character as the Eye is a part of Strange. If the Time Stone is behind the source of his power, hopefully he has other means to conjure up his magic after Thanos takes it.
The film's trailers and TV spots have already shown Strange messing with time briefly, so it certainly seems plausible that this connection could be made. However, this is still not confirmed and will not be until during or after Doctor Strange is released. Time will tell whether or not this is the case, but everyone will no for certain in just a few weeks.
Doctor Strange opens November 4, 2016; Guardians of the Galaxy Vol. 2 – May 5, 2017; Spider-Man: Homecoming – July 7, 2017; Thor: Ragnarok – November 3, 2017; Black Panther – February 16, 2018; Avengers: Infinity War – May 4, 2018; Ant-Man and the Wasp – July 6, 2018; Captain Marvel– March 8, 2019; Untitled Avengers – May 3, 2019; and as-yet-untitled Marvel movies on July 12, 2019, and on May 1, July 10, and November 6 in 2020.