Not all images available through these search engines are available under a Creative Commons license, however Bing and Google Images both allow for a way to limit your search results to appropriately licensed images:
Bing
Limit your results to appropriately licensed images by clicking on "License" in the menu below the search box, after first typing in your search term(s). Though users are not able to limit by specific types of Creative Commons licenses, there are definitions of their categories to help you match the license to your needs. You can also limit by Public Domain images.
Google Images
Limit your search results to only images available under a Creative Commons license by doing your search in the Google Image search bar and then on the results page, click on search tools just below the search box. A further drop down menu will then appear with usage rights as one of the options. From there, users can limit results to the proper rights.