This is a randomized (the study medication is assigned by chance), open-label (all people know the identity of the intervention), multicenter study. The study will consist of a screening phase up to 6 weeks, open-label treatment phase of 8 weeks or 12 weeks, and post-treatment follow up phase up to 24 weeks after end of treatment. Approximately 300 participants will be randomly allocated in a 1:1 ratio to receive 150 mg simeprevir in combination with 400 mg sofosbuvir once daily either for 12 weeks (Arm 1) or 8 weeks (Arm 2). Safety evaluations will include assessment of adverse events, clinical laboratory tests, vital signs, and physical examination. The maximum study duration for each participant will be approximately 42 weeks.