The hit occurred during Thursday night's game, when Harrison lowered his head and struck McCoy in the facemask after the quarterback scrambled out of the pocket and threw a pass.
Harrison was penalized for roughing the passer and McCoy suffered a concussion because of the hit. The league announced the suspension Tuesday.
This marks Harrison's fifth illegal hit against a quarterback in the past three seasons, classifying him as a repeat offender.
The 2011 League Policies for Players manual states: "Players who were fined for violations in 2009 or 2010, and whose fines were either partially or fully upheld, will be considered second and/or repeat offenders under this policy."
Harrison may not practice or be at the team facility or stadium during the suspension, and will not be allowed to return until he is reinstated on December 20.