The European Union hit Alphabet Inc.’s Google with a record $5 billion antitrust fine and ordered changes that could reshape the business model underlying its biggest growth engine: mobile phones.

In another rebuke to one of Silicon Valley’s tech giants, the bloc’s antitrust regulator found Wednesday that Google had abused the dominance of its Android operating system, which runs more than 80% of the world’s smartphones, to promote and entrench the company’s cash-cow search engine.

The EU ordered Google to stop making phone manufacturers pre-install its search app and the Chrome web browser if they want to pre-install Google’s Play store, which is the dominant way to download Android apps. The bloc also ordered Google to end restrictions that discourage manufacturers from selling devices that run unofficial versions of Android.

Google, which said it would appeal the decision, has rejected the EU’s contentions since the bloc issued formal charges over two years ago. Google said Android, which is free for manufacturers to use, has increased competition among smartphone makers, lowering prices for consumers. Google also said the allegation that it stymied competing apps is false because manufacturers typically install many rival apps on Android devices—and consumers can download others.

Wednesday’s fine tops the EU’s previous record penalty of 2.42 billion Euros when the bloc last year ordered Google to stop using its search engine to favor its own product-advertising service over others.