Install the mesa package.
pacman -Syu mesa
Edit /etc/mkinitcpio.conf
MODULES=(i915)
Then build initramfs
mkinitcpio -P
Edit /etc/X11/xorg.conf.d/20-intel.conf Option 1
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "TearFree" "true"
EndSection
Option 2
Section "Device"
Identifier "Intel Graphics"
Driver "intel"
Option "AccelMethod" "sna"
Option "TearFree" "true"
Option "SwapbuffersWait" "true"
Option "DRI" "2"
EndSection
Reboot