The 20-year-old attacking midfielder joins D.C. from Belgian second-division side Vise.
The 5-foot-8, 148-pound Alam joins D.C. from Belgian second-division side Vise, where he has played sparingly this season. Alam has played 51 minutes in five substitute appearances, most recently playing 17 minutes in a draw against Oudenaarde on Oct. 27. He made five appearances in the 2011-12 season for Vise, including three starts.
"Syamsir is a young, attacking midfielder with good technical ability, and we look forward to having him on loan with us," said D.C. United general manager Dave Kasper said in a statement.