This study will assess the efficacy and safety of tocilizumab compared with placebo in participants with SSc across approximately 120 planned global study sites. The study will consist of a 48-week, double-blind, placebo-controlled period followed by a 48-week open-label treatment period. Participants will be assigned, in a 1:1 ratio, to double-blind treatment with active tocilizumab or matching placebo. In the open-label period, eligible participants from either arm may receive active tocilizumab.