/usr/lib/llvm-3.5/include/clang/Frontend/ is in libclang-3.5-dev 1:3.5~svn201651-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/llvm-3.5/include/clang/Frontend/ASTConsumers.h
/usr/lib/llvm-3.5/include/clang/Frontend/ASTUnit.h
/usr/lib/llvm-3.5/include/clang/Frontend/ChainedDiagnosticConsumer.h
/usr/lib/llvm-3.5/include/clang/Frontend/ChainedIncludesSource.h
/usr/lib/llvm-3.5/include/clang/Frontend/CodeGenOptions.def
/usr/lib/llvm-3.5/include/clang/Frontend/CodeGenOptions.h
/usr/lib/llvm-3.5/include/clang/Frontend/CommandLineSourceLoc.h
/usr/lib/llvm-3.5/include/clang/Frontend/CompilerInstance.h
/usr/lib/llvm-3.5/include/clang/Frontend/CompilerInvocation.h
/usr/lib/llvm-3.5/include/clang/Frontend/DependencyOutputOptions.h
/usr/lib/llvm-3.5/include/clang/Frontend/DiagnosticRenderer.h
/usr/lib/llvm-3.5/include/clang/Frontend/FrontendAction.h
/usr/lib/llvm-3.5/include/clang/Frontend/FrontendActions.h
/usr/lib/llvm-3.5/include/clang/Frontend/FrontendDiagnostic.h
/usr/lib/llvm-3.5/include/clang/Frontend/FrontendOptions.h
/usr/lib/llvm-3.5/include/clang/Frontend/FrontendPluginRegistry.h
/usr/lib/llvm-3.5/include/clang/Frontend/LangStandard.h
/usr/lib/llvm-3.5/include/clang/Frontend/LangStandards.def
/usr/lib/llvm-3.5/include/clang/Frontend/LayoutOverrideSource.h
/usr/lib/llvm-3.5/include/clang/Frontend/LogDiagnosticPrinter.h
/usr/lib/llvm-3.5/include/clang/Frontend/MigratorOptions.h
/usr/lib/llvm-3.5/include/clang/Frontend/MultiplexConsumer.h
/usr/lib/llvm-3.5/include/clang/Frontend/PreprocessorOutputOptions.h
/usr/lib/llvm-3.5/include/clang/Frontend/SerializedDiagnosticPrinter.h
/usr/lib/llvm-3.5/include/clang/Frontend/TextDiagnostic.h
/usr/lib/llvm-3.5/include/clang/Frontend/TextDiagnosticBuffer.h
/usr/lib/llvm-3.5/include/clang/Frontend/TextDiagnosticPrinter.h
/usr/lib/llvm-3.5/include/clang/Frontend/Utils.h
/usr/lib/llvm-3.5/include/clang/Frontend/VerifyDiagnosticConsumer.h
/usr/lib/llvm-3.5/include/clang/FrontendTool/Utils.h