A Phase Ib/II Study Evaluating the Safety and Efficacy of Obinutuzumab in Combination With Polatuzumab Vedotin and Lenalidomide in Patients With Relapsed or Refractory Follicular Lymphoma and Rituximab in Combination With Polatuzumab Vedotin and Lenalidomide in Patients With Relapsed or Refractory Diffuse Large B-Cell Lymphoma

All participants will receive lenalidomide oral capsules at doses of 10, 15, or 20 milligrams (mg) on Days 1 to 21 of each 28-day cycle for up to 6 Cycles in dose escalation phase followed by post-induction treatment at a dose of 10 mg once daily on Days 1 to 21 of each subsequent 28-day cycle. Post-induction lenalidomide may continue for up to 12 months until disease progression or unacceptable toxicity for participants with R/R FL and up to 6 months until disease progression or unacceptable toxicity for participants with R/R DLBCL.

Participants will receive a fixed dose of obinutuzumab, 1000 mg via intravenous (IV) infusion to be given on Days 1, 8 and 15 of Cycle 1 and on Day 1 of Cycles 2 to 6 followed by post-induction treatment at a dose of 1000 mg via IV infusion on Day 1 of every other month for up to 24 months until disease progression or unacceptable toxicity.

Participants with R/R FL will receive polatuzumab vedotin via IV infusion at doses of 1.4 or 1.8 milligrams per kilogram (mg/kg) on Day 1 of each 28-day cycle for up to 6 months during induction treatment. Participants wit R/R DLBCL will receive polatuzumab vedotin via IV infusion at dose 1.8 mg/kg on Day 1 of each 28-day cycle for up to 6 months during induction treatment.

Participants will receive a fixed dose of rituximab, 375 mg/m\^2 via intravenous (IV) infusion to be given on Days 1 of Cycle 1 to 6 followed by post-induction treatment at a dose of 375 mg/m\^2 via IV infusion on Day 1 of every other month for up to 6 months, until disease progression or unacceptable toxicity.