Efficacy, Safety, and Tolerability Study of Pirfenidone in Combination With Sildenafil in Participants With Advanced Idiopathic Pulmonary Fibrosis (IPF) and Intermediate or High Probability of Group 3 Pulmonary Hypertension

Inclusion Criteria: * Diagnosis of IPF for at least 3 months prior to Screening * Confirmation of IPF diagnosis by the investigator in accordance with the 2011 international consensus guidelines at screening * Advanced IPF (defined as a measurable carbon monoxide diffusing capacity \[DLCO\] less than or equal to (\<=)40% of predicted value at Screening) and intermediate or high probability of group 3 pulmonary hypertension (PH) * Participants receiving pirfenidone for at least 12 weeks, at a dose in the range of 1602 to 2403 mg/day for at least 4 weeks prior to Screening and must not have experienced either a new or ongoing adverse event of National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) (version 4.03) Grade 2 or higher and considered by the investigator to be related to pirfenidone, or an interruption of pirfenidone treatment of greater than (\>)7 days for any reason * WHO Functional Class II or III at Screening * 6MWD of 100 to 450 meters at screening * Women of childbearing potential and for men who are not surgically sterile agreement to remain abstinent or use of contraceptive measures Exclusion Criteria: * History of any of the following types of PH: Group 1 (PAH); Group 1 (pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis); Group 2 (left-heart disease); Group 3 (due to conditions other than interstitial lung disease, including chronic obstructive pulmonary disease \[COPD\], sleep-disordered breathing, al…