Updating this answer as Lollipop OS is officially released with support libraries, which you can use inside your project to provide compatibility to older versions.
Support library: v7 appcompat library
This library adds support for the Action Bar user interface design pattern. This library includes support for material design user interface implementations.
If you are using Android Studio then you just need to include below dependency identifier:
com.android.support:appcompat-v7:21.0.+