/usr/include/llvm-6.0/llvm/Target/ is in llvm-6.0-dev 1:6.0-1ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/llvm-6.0/llvm/Target/GenericOpcodes.td
/usr/include/llvm-6.0/llvm/Target/GlobalISel/
/usr/include/llvm-6.0/llvm/Target/GlobalISel/RegisterBank.td
/usr/include/llvm-6.0/llvm/Target/GlobalISel/SelectionDAGCompat.td
/usr/include/llvm-6.0/llvm/Target/GlobalISel/Target.td
/usr/include/llvm-6.0/llvm/Target/Target.td
/usr/include/llvm-6.0/llvm/Target/TargetCallingConv.td
/usr/include/llvm-6.0/llvm/Target/TargetIntrinsicInfo.h
/usr/include/llvm-6.0/llvm/Target/TargetItinerary.td
/usr/include/llvm-6.0/llvm/Target/TargetMachine.h
/usr/include/llvm-6.0/llvm/Target/TargetOptions.h
/usr/include/llvm-6.0/llvm/Target/TargetSchedule.td
/usr/include/llvm-6.0/llvm/Target/TargetSelectionDAG.td