The move comes after Simpson sat out the 2014 season under a cloud of legal ramifications.
The 6-foot-1, 193-pound Simpson, 29, is perhaps best known for his front-flip touchdown catch and run for the Bengals against the Arizona Cardinals in 2011, but he also has a body of work. Originally a second-round pick of the Bengals in 2008 out of Coastal Carolina, Simpson has 145 catches for 2,004 yards and eight TDs in 57 career games (36 starts).
In 2013, with the Vikings, he caught 48 passes for a career-high 726 yards and a TD.
He is infamously known, though, for the strange circumstances under which he did not play in 2014. Simpson was initially slapped with a three-game suspension to begin last season for a reckless driving arrest but was cut by Minnesota in the midst of said suspension last September. He already had been suspended once by the Vikings for a marijuana-related arrest in 2011, and then was cited in July 2014 for misdemeanor charges of marijuana possession, driving with an open bottle and violating limited license restrictions after he was pulled over.
Simpson, then, having not played last year, faces potential additional discipline from the NFL if he does make the 49ers roster.
Bringing in a player with Simpson's baggage would seem to fly in the face of 49ers CEO Jed York's decree to "win with class."
The 49ers also reportedly brought in one of their own former pass catchers for a visit this week in Ted Ginn Jr.
Last year, the Niners brought back Lloyd, who had not played the year before, and he averaged 21 yards per catch with 14 receptions for 294 yards and a TD. And in 2012, they brought in Randy Moss, who was out of football in 2011
Also Thursday, the 49ers officially announced they had agreed to terms with defensive tackle Darnell Dockett.