Mac OS X does appear to mount with atime but I happened to use this:

    $ cat /Library/LaunchDaemons/com.nullvision.noatime.plist    
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" 
            "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
    <plist version="1.0">
        <dict>
            <key>Label</key>
            <string>com.nullvision.noatime</string>
            <key>ProgramArguments</key>
            <array>
                <string>mount</string>
                <string>-vuwo</string>
                <string>noatime</string>
                <string>/</string>
            </array>
            <key>RunAtLoad</key>
            <true/>
        </dict>
    </plist>

I don't know if there's anything like relatime.