A Study of the Combination of Ibrutinib Plus Venetoclax Versus Chlorambucil Plus Obinutuzumab for the First-line Treatment of Participants With Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Lymphoma (SLL)

Inclusion Criteria:

• Adult participants who are: (a) greater than or equal to (>=) 65 years old or, (b) 18 to 64 years old and have at least 1 of the following:

1. Cumulative Illness Rating Scale (CIRS) score > 6

2. Creatinine clearance (CrCl) estimated less than (<) 70 milliliter per minute (mL/min) using Cockcroft-Gault equation

• Diagnosis of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL)that meets International Workshop on Chronic Lymphocytic Leukemia (iwCLL) criteria

• Measurable nodal disease (by computed tomography [CT]), defined as at least onelymph node > 1.5 centimeter (cm) in longest diameter

• Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) Grade less than orequal to (<=) 2

• Active CLL/SLL requiring treatment per the iwCLL criteria

Exclusion Criteria:

• Prior anti-leukemic therapy for CLL or SLL

• Presence of deletion of the short arm of chromosome 17 (del17p) or known TP53mutation detected at a threshold of >10 percent (%) variable allele frequency (VAF)

• Major surgery within 4 weeks of first dose of study treatment

• Known bleeding disorders (example, von Willebrand's disease or hemophilia)

• Central nervous system (CNS) involvement or suspected Richter's syndrome