I have successfully built the aosp_x86_64 from lunch combo.
Now I want to customize the build by adding overlay folder. But I couldn't find it's corresponding device tree folder. Please let me know the location of the folder.
So, I struggled with this for a couple of days and finally found aosp_x86_64.mk in $ANDROID_SOURCE/build/target/product folder.
I opened the file and added DEVICE_PACKAGE_OVERLAYS attribute in it and set it to a path I liked. Worked like a charm.