Cleary Gottlieb Steen & Hamilton lawyers helped guide Google toward completing the largest acquisition in the company’s history—the $12.5 billion acquisition of mobile-device maker Motorola Mobility Holdings Inc., the firm announced yesterday.

In buying the Schaumburg, Illinois–based handset manufacturer, Google—whose Android operating system is used in many Motorola devices—will assume control of one of the mobile industry’s strongest patent portfolios, company executives said.