The 27-year-old can go straight into the side away to Wycombe on Saturday.
Cheltenham are without regular stopper Scott Brown, who cannot play against his parent club Wycombe, while Callum Kitscha is sidelined through injury.
The deal was permitted because, while 19-year-old keeper Rhys Lovett is available, he is yet to play a first-team game for Gary Johnson's side.
Former Bolton trainee Lainton will train with the Cheltenham squad on Friday.
Find all the latest football transfers on our dedicated page.
League Two Cheltenham Town have signed Bury goalkeeper Rob Lainton on a seven-day emergency loan deal.