The purpose of this study is to compare the antiretroviral activity of MK-1439A, a single-tablet, once-daily (q.d.) fixed-dose combination (FDC) containing MK-1439 100 mg + lamivudine 300 mg + tenofovir disoproxil fumarate 300 mg, with ATRIPLA™, a single-tablet FDC containing efavirenz 600 mg + emtricitabine 200 mg + tenofovir disoproxil fumarate 300 mg, in treatment-naive participants infected with HIV. The primary hypothesis is that MK-1439A q.d. is non-inferior to ATRIPLA™ q.d. as assessed by the proportion of participants with HIV-1 ribonucleic acid (RNA) <50 copies/mL (by the Abbott RealTime HIV-1 Assay) at Week 48.