For more information regarding Bristol-Myers Squibb Clinical Trial participation, please visit www.BMSStudyConnect.com  Inclusion Criteria:  Diagnosis of primary myelofibrosis (PMF), post-essential thrombocythemia (ET) or post-polycythemia vera (PV) myelofibrosis Treatment-related toxicities from prior therapy resolved to Grade 1 or pre-treatment baseline or determined to be irreversible prior to study treatment Must agree to follow specific methods of contraception, if applicable  Exclusion Criteria:  Women who are pregnant or breastfeeding at screening Any significant acute or uncontrolled chronic medical illness  Other protocol-defined inclusion/exclusion criteria apply