Any player on the team's 40-man roster is eligible for a September callup. In the case of LaHair, he was added to the team's 40-man roster, which stands at 38.
Manager Mike Quade said LaHair will play in the outfield and first base.
Andrew Cashner will be removed from the 60-day DL on Tuesday, when he'll be called up from Triple-A Iowa. He has one more rehab outing on Saturday and then will be added to the 40-man roster.
Other likely callups include infielder D.J. LeMahieu, and RHP Rafael Dolis, who is a closer at Double-A Tennessee.
Possible callups include LHP John Gaub and right-hander Alberto Cabrera.
It's unknown whether catchers Wellington Castillo or Steve Clevenger will be considered. Castillo has been on and off the DL.
Top prospect Brett Jackson is not on the 40-man roster. He's the Cubs' most attractive prospect, but with 22 games left on the schedule, would this be the right time to bring him to the majors?
The organization's philosophy has been to move Jackson up when he is ready to play at the major league level every day. This type of addition would be difficult for manager Mike Quade, who will have to tell Alfonso Soriano and Marlon Byrd that their playing time may be severely cut for the last three weeks of the season.
"You figure out each day how you're going to do it," Quade said. "You talk to your veterans and you look for your opportunities while mixing and matching.
"I would argue that any experience at this level has got to help you down the road."
Quade's quandary is trying to win as many games as possible in order to give the next general manager of the team something to evaluate his 1-plus years as Cubs manager. The win-loss ledger is the final evaluation of any baseball man, and that situation may alter the way Quade uses his players.
Quade has one year remaining at $1 million for 2012.