Subjects who meet the eligibility criteria will be randomly assigned to one of the following blinded study treatment regimens in equal proportion (1:1): UMEC 62.5 mcg once-daily and Placebo once-daily. Approximately 230 subjects (115 subjects per treatment) will be randomized in order to complete at least 206 evaluable subjects. The total duration of the study will be approximately 14 weeks for each subject.