build.gradle

// add this to the general build.gradle, not in the subproject's build.gradle
// improved version of Xavier's tip http://tools.android.com/tech-docs/new-build-system/tips#TOC-Improving-Build-Server-performance.

// usage example default, preDex will be enabled: gradle clean build
// usage example disabling preDex: gradle clean build -PpreDexEnable=false
// preDexEnable parameter's value can be set as property of Continuous Integration build config
// this is the main difference from Xavier's workaround where he doing only hasProperty check

project.ext {
    project.ext.preDexLibs = !'false'.equals(project.properties['preDexEnable'])
}

subprojects {
    project.plugins.whenPluginAdded { plugin ->
        if ('com.android.build.gradle.AppPlugin'.equals(plugin.class.name)
         || 'com.android.build.gradle.LibraryPlugin'.equals(plugin.class.name)) {
            android {
                dexOptions {
                    javaMaxHeapSize = '4g'
                    preDexLibraries = rootProject.ext.preDexLibs
                }
            }
        }
    }
}