Inclusion Criteria:

          -  Histological confirmation of relapsed/refractory B-cell NHL, CD20+

               -  NOTE: patients with small lymphocytic lymphoma (SLL) are eligible however
                  patients with chronic lymphocytic leukemia (CLL) are not eligible

               -  Waldenstrom macroglobulinemia patients are not eligible; aggressive lymphoma
                  patients who are transplant eligible must have undergone a transplant

               -  The biopsy confirming relapse can be up to 24 weeks prior to registration as long
                  as there is no intervening therapy

          -  Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0, 1, or 2

          -  Absolute neutrophil count (ANC) >= 1500/mm^3

          -  Platelet count >= 75,000/mm^3

          -  Hemoglobin >= 8.0 g/dL

          -  Total bilirubin =< 1.5 X upper limit of normal (ULN) or if total bilirubin is > 1.5 X
             ULN, the direct bilirubin =< ULN

          -  Alkaline phosphatase =< 3 X ULN unless due to direct lymphoma involvement, and then =<
             5 X ULN

          -  Aspartate transaminase (AST) =< 3 X ULN unless due to direct lymphoma involvement, and
             then =< 5 X ULN

          -  Calculated creatinine clearance must be >= 30 ml/min using the Cockcroft-Gault formula

          -  Life expectancy >= 3 months

          -  Ability to provide written informed consent

          -  Willing to return to enrolling institution for follow-up (during the treatment and
             observation phases of the study)

          -  Willing to provide tissue for central review blood samples for correlative research
             purposes

          -  No other therapy with demonstrated clinical benefit in relapsed/refractory B-cell NHL
             available to the patient

          -  Negative pregnancy test done =< 7 days prior to registration, for women of
             childbearing potential only

        Exclusion Criteria:

          -  Any of the following:

               -  Pregnant women

               -  Nursing women

               -  Men or women of childbearing potential who are unwilling to employ adequate
                  contraception

          -  Active central nervous system (CNS) lymphoma or cerebrospinal fluid involvement with
             malignant lymphoma cells that requires therapy

          -  Co-morbid systemic illnesses or other severe concurrent disease which, in the judgment
             of the investigator, would make the patient inappropriate for entry into this study or
             interfere significantly with the proper assessment of safety and toxicity of the
             prescribed regimens

          -  Uncontrolled intercurrent illness including, but not limited to, ongoing or active
             infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
             arrhythmia, or psychiatric illness/social situations that would limit compliance with
             study requirements

          -  Patients who received most recent therapy =< 4 weeks prior to registration; NOTE: use
             of systemic steroid therapy is allowed pretreatment

          -  Receiving any other investigational agent which would be considered as a treatment for
             the primary neoplasm

          -  Patients must be disease-free of prior invasive malignancies for > 5 years prior to
             registration with the exception of curatively-treated basal cell or squamous cell
             carcinoma of the skin or carcinoma in situ of the cervix

          -  Patients with >= 25% of the bone marrow radiated for other diseases

          -  Other medical conditions including but not limited to:

               -  History of liver disease such as cirrhosis, chronic active hepatitis, chronic
                  persistent hepatitis or hepatitis B or C

               -  Active infection requiring parenteral antibiotics

               -  New York Heart Association class II-IV congestive heart failure (serious cardiac
                  arrhythmia requiring medication)

               -  Myocardial infarction or unstable angina =< 6 months prior to registration

               -  Congestive heart failure requiring use of ongoing maintenance therapy for
                  life-threatening ventricular arrhythmias

               -  Clinically significant peripheral vascular disease

               -  History of CNS disease (e.g., primary brain tumor, vascular abnormalities, etc.),
                  clinically significant stroke or transient ischemic attack (TIA) =< 6 months
                  prior to registration, seizures not controlled with standard medical therapy

               -  Neuropathy ˃ grade 3

          -  Administration of strong CYP2C8 or CYP3A4 inhibitors or inducers =< 10 days prior to
             registration