Freeman, a 2009 first-round draft pick, started 59 games for Tampa Bay and one with Minnesota, but he has not played in the league for more than two years.
Matt Hasselbeck, who started in place of Luck the past six games, won't play due to an injured throwing shoulder, and third-stringer Charlie Whitehurst landed on injured reserve Monday with a hamstring injury.
Freeman and Lindley were signed on Tuesday, while Morris has been with the Colts since Dec. 24.
"They've done a great job," coach Chuck Pagano said earlier this week. "You can imagine coming off the street and they know zero. We're not going to throw everything at them, so we cut [the playbook] down."
The Colts (7-8), who have won 13 of their past 14 meetings against the Titans, are still alive in the playoff hunt entering the final week of the season.
Indianapolis is one game back of Houston for first place in the division. While a victory combined with a Texans loss to Jacksonville creates a tie in the standings, the Colts need seven other results to go their way in order to claim the tiebreaker for strength of schedule.
ESPN Staff Writer Mike Wells and The Associated Press contributed to this report.