Bennett moves to Stockport on-loan to the end of the season.
Stockport boss Dave Challinor said: "Rhys is someone we know and who knows us. He spent a couple of months with us last season as part of an arrangement we had with Man United to get some younger players into our environment to train.
"It's fair to say he made a lasting impression on all of the staff not just in terms of his ability, but as a character and personality in being mature and having an understanding of the game. When the opportunity came to bring him back in, especially due to our current situation, it was something we were all keen to do and it's great to have him back with us."
Director of Football, Simon Wilson also told the club's website: “This is a good example of how clubs can work effectively with each other. Rhys trained with us last season for a month on work experience, which was part of a wider initiative by Manchester United to give their players some preparation for a loan in senior football.
“The feedback all round from that was excellent, Rhys has kicked on since with United's first-team but is now available for loan and having had that initial exposure to each other it was an easy win for all parties. He gives us good depth across defensive positions.
"The previous time together gives us all a head start and I'm sure Rhys will settle quickly and contribute to our important remaining games this season."