The structural relaxation of a glass-forming simple liquid, 3-methylpentane, is studied by triplet state solvation dynamics as a function of the distance from the surface in porous silica. By bonding the optical probes to the pore surface, we observe interfacial dynamics which are 3 orders of magnitude slower compared with the bulk, equivalent to a surface induced glass transition. Consistent with length scales of cooperativity, these effects disappear for distances from the surface exceeding a few nanometers.