SCCM 2012 - User collection based on OU membership

Inside System Center Configuration Manager:

Create a new User collection

Give it a descriptive name, set your limiting collection as the broadest one you have.

After clicking Next, add a Query rule,

Resource class: User Resource.  Click on edit query statement, then Show query language and paste in the following:

select SMS_R_USER.ResourceID,SMS_R_USER.ResourceType,SMS_R_USER.Name,SMS_R_USER.UniqueUserName,SMS_R_USER.WindowsNTDomain from SMS_R_User where SMS_R_User.UserOUName = "<YOUR DOMAIN>/<YOUR OU>"

Be sure to edit your own domain and OU structure.. i.e.

domain/people/employees/engineering

domain/people/employees/hr

etc,etc