Libby will bolster a squad shorn of three players for the season opener against Sussex on Sunday.
Rob Keogh, Steven Crook and Rob Newton will all be unavailable for the County Championship Division Two curtain raiser at the County Ground.
Libby is likely to appear in that game, with the 23-year-old having a good history against Sussex.
He scored 108 on his debut against them and is also a reliable bowler with best figures of one for 18.
And Northants head coach David Ripley said: “We have three players unavailable for our first few games with Newton, Crook and Keogh ruled out for selection therefore we are very pleased and grateful to Nottinghamshire for allowing Jake to join us on a month’s loan.”