Gilead Sciences Inc. is planning to hire industry veteran Daniel O’Day to take the helm and help the drug company revive sales and recover from a disappointing deal, according to people familiar with the matter.

Mr. O’Day, whose hiring could be announced as soon as Monday, would become Gilead CEO after a long career at Switzerland’s Roche Holding AG, most recently running its pharmaceuticals group, the people said. In the role, Mr. O’Day oversaw successful launches of several new cancer and other drugs, and turned the business...