A Study to Evaluate the Efficacy and Safety of Ocrelizumab in Adults With Primary Progressive Multiple Sclerosis

Inclusion Criteria: * EDSS score at screening and baseline \>= 3.0 to 8.0, inclusive * Disease duration from the onset of MS symptoms relative to randomization date: Less than 20 years in participants with an EDSS score at screening 7.0 - 8.0 Less than 15 years in participants with an EDSS at screening 5.5 - 6.5 Less than 10 years in participants with an EDSS at screening \<= 5.0 * Documented history or presence at screening of at least one of the following laboratory findings in a cerebrospinal fluid specimen: Elevated immunoglobulin G (IgG) index or one or more IgG oligoclonal bands detected by isoelectric focusing * Screening and baseline 9-HPT completed in \> 25 seconds (average of the two hands) * Neurological stability for ≥ 30 days prior to baseline * Ability to complete the 9-HPT within 240 seconds with each hand at screening and baseline * Neurological stability for \>/= 30 days prior to baseline * Participants previously treated with immunosuppressants, immunomodulators, or other immunomodulatory therapies must undergo an appropriate washout period according to the local label of the immunosuppressant/immunomodulatory drug used * For women of childbearing potential: agreement to remain abstinent (refrain from heterosexual intercourse) or use adequate contraceptive methods during the treatment period and for 6 or 12 months after the final dose of ocrelizumab. Adherence to local requirements, if more stringent, is required. * For female participants without reprodu…