They've changed that name a number of times. On the S2 (gray UI version) it literally had a checkbox "Smart IR" by the IR settings
On the newer S3 (blue /White UI) its simply "Auto" under Illumination, along with the "Illumination Overexposure Remover" control
On the newer S3 (blue /White UI) its simply "Auto" under Illumination, along with the "Illumination Overexposure Remover" control