Efficacy and Safety of Ledipasvir/Sofosbuvir, With or Without Ribavirin, in HCV Infected Participants Who Have Failed Prior Treatment With Sofosbuvir-based Therapies

Key Inclusion Criteria: * HCV RNA \> 15 IU/mL at screening * HCV genotype 1 or 4 * Chronic HCV infection (≥ 6 months) * Prior virologic failure after treatment with SOF in combination with simeprevir (SMV) ± RBV or with RBV ± pegylated interferon (PEG) * Cirrhotic and non-cirrhotic as determined by standard methods * Male and female individuals of childbearing potential who engage in heterosexual intercourse must agree to use protocol specified method(s) of contraception Key Exclusion Criteria: * Prior exposure to approved or experimental non-structural protein (NS5A) inhibitors * Prior exposure to nucleos(t)ide polymerase inhibitors, other than SOF * Pregnant or nursing female or male with pregnant female partner * Coinfection with HIV or hepatitis B virus * Current or prior history of clinical hepatic decompensation * Hepatocellular carcinoma or other malignancy (with exception of certain resolved skin cancers) * Chronic use of systemic immunosuppressive agents * History of clinically significant illness or any other medical disorder that may interfere with individual's treatment, assessment or compliance with the protocol Note: Other protocol defined Inclusion/Exclusion criteria may apply.