Roof-mounted occupant restraint system

A restraint system (10) for helping to protect an occupant (60) of a vehicle (20) having a roof (32) and a cabin (40) with a seat (50) for the occupant (60) includes an airbag (120) having a stored condition within the roof (32) and being inflatable to a deployed condition extending into the cabin (40) aligned with the seat (50). A tether (140) includes a first end (142) connected to the airbag (120) and a second end (144) connected to the vehicle (20). Tear stitching (170) interconnects overlying portions (152, 154) of the tether (140). The tear stitching (170) is rupturable in response to occupant (60) penetration into the deployed airbag (120) to permit the interconnected overlying portions (151, 154) to move relative to one another such that the tether (140) lengthens.