Study ING116529 is a multicenter, randomized, study with an initial 7 day placebo- controlled, functional monotherapy phase to quantify the antiviral activity attributable to dolutegravir (DTG) in HIV-1 infected, ART-experienced adults who are experiencing virological failure on an Integrase inhibitor containing regimen (current RAL or ELV failures), with evidence of genotypic resistance to RAL or ELV at study entry. Thirty subjects will be randomized (1:1) to receive either DTG 50mg BID (Arm A) or Placebo (Arm B) with the current failing regimen for 7 days (RAL or ELV should be discontinued prior to dosing with DTG). At Day 8, subjects from both arms will enter an open label phase and receive open label DTG 50mg BID with an optimized background regimen containing at least one fully active drug.