The 19-year-old Blues defender, who started his footballing career at Fir Park, will remain with the Scottish Premier League outfit until the end of the season.
"I am pleased to get Fraser here for another few months; he will provide good competition for the lads at the back," Motherwell boss Stuart McCall told the club's official website
"He's young and still learning the game and we've asked him to fill in all over the place and he has done well for himself.
"He was excellent against Georgios Samaras at Celtic Park during the week; his recovery pace is vital in games like that.
"If we want to finish in the top six and push for European places, then everyone will have a role to play and Fraser will be a big part in that."