This is a single-arm (all patients will receive the study drug) study to evaluate the efficacy and safety of ibrutinib in patients with mantle cell lymphoma (MCL) who have received at least 1 rituximab-containing chemotherapy regimen and who progressed after bortezomib therapy. Approximately 110 eligible patients will be enrolled. During the treatment phase, patients will receive 560 mg of ibrutinib by mouth once daily continuously until disease progression, unacceptable toxicity, or study end, whichever occurs first. Treatment will be continuous (without interruption) and self-administered at home. Doses can be held or reduced based on the severity of and the recovery from side effects of the study drug. The sponsor will ensure that patients benefiting from treatment with ibrutinib will be able to continue treatment after the end of the study. Data will be collected on disease response to the treatment, on progression-free survival, overall survival, and subsequent anti-MCL therapies. Serial pharmacokinetic (study of what the body does to a drug) samples will be collected as detailed in the protocol. Safety will be monitored throughout the study. An interim analysis of the pharmacokinetic data will occur approximately 3 months after the scheduled pharmacokinetic sampling in Cycles 1 and 2 has been completed. Data will be analyzed 1 year after the last patient is enrolled for the primary analysis and 2 years after last patient is enrolled for the final follow-up.