The 25-year-old, who has previously played for Notts County, will remain with the club until January, with the option of an extension.
"Fitness-wise, he is way behind the other players - he needs to be playing games - but I know what he's all about and he's a good player at this level," manager John Sheridan told the club's official website.
"He has played against my teams a couple of times and he has been strong. He has got a presence about him."
Bencherif had spent the last week on trial at Home Park.