Ruxolitinib Phosphate and Decitabine in Treating Patients With Relapsed or Refractory or Post Myeloproliferative Acute Myeloid Leukemia

Inclusion Criteria: * Diagnosis of AML (World Health Organization \[WHO\] classification definition of \>= to 20% blasts) * In the phase I portion of the study all patients with relapsed or refractory AML are eligible; for the Phase II portion of the study, patients must have AML progressing from prior MPN (MPN-BP) or have myelodysplastic syndrome (MDS)/MPN with more than 20% blasts; temporary prior measures to control blood counts, such as apheresis or Hydrea are allowed; patients with newly diagnosed or previously treated disease are eligible as long as prior therapy does not include hypomethylating agents; prior therapy for ruxolitinib for MPN is allowed * Serum biochemical values with the following limits unless considered due to leukemia: * Creatinine =\< 1.5 mg/dl * Total bilirubin =\< 1.5 mg/dL, unless increase is due to hemolysis or congenital disorder * Transaminases (serum glutamate pyruvate transaminase \[SGPT\]) =\< 2.5 x upper limit of normal (ULN) * Ability to take oral medication * Ability to understand and provide signed informed consent * Performance status =\< 3, unless directly related to disease process as determined by the principal investigator Exclusion Criteria: * Any coexisting medical condition that in the judgment of the treating physician is likely to interfere with study procedures or results including uncontrolled severe infections, as well as uncontrolled cardiac disease, or other organ dysfunction; patients with history of tuberculosis, human immunodeficiency virus (HIV) or hepatitis B and C are excluded * Nursing women, women of childbearing potential with positive blood pregnancy test within 30 days of study start, or women of childbearing potential who are not willing to maintain adequate contraception (such as birth control pills, intrauterine device \[IUD\], diaphragm, abstinence, or condoms by their partner) over the entire course of the study * Incomplete recovery from any prior surgical procedures or had surgery within 4 weeks prior to study entry, excluding the placement of vascular access * Active clinically serious and uncontrolled infection