Could not find builder.jar (com.android.tools.build:builder:3.1.0)

Go to File>Setting>Build,Execution,Deployment>Gradle>Android Studio>> and Check mark this:: Enable Embedded repository and Click Ok. Then, Rebuild the Project.

or

go to Terminal and type "gradlew cleanBuildCache" to clear the cache. The cache is in USERNAME.ANDROID\BUILD CACHE Directory.

And Rebuild.

Accepted answer did not work for me, so I changed the class path line in gradle (project : project name) and issue is gone.

classpath 'com.android.tools.build:gradle:3.1.2'

Try deleting ~/.gradle folder and building the project again. Gradle will download that.