diff --git a/.appveyor.yml b/.appveyor.yml
index a13f2fc5..0b89cb11 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -26,9 +26,9 @@ build_script:
         python waf configure --msvc_version="msvc 15.0"
         python waf build
         mkdir "${dir}\build\release\bin" -ea 0
-        mkdir "${dir}\build\release\lib\LLVM-5.0.1-win64\lib\clang\5.0.1\"
+        mkdir "${dir}\build\release\lib\LLVM-6.0.0-win64\lib\clang\6.0.0\"
         copy "build\release\bin\*" "${dir}\build\release\bin"
-        copy -recurse "build\LLVM-5.0.1-win64\lib\clang\5.0.1\include" "${dir}\build\release\lib\LLVM-5.0.1-win64\lib\clang\5.0.1\"
+        copy -recurse "build\LLVM-6.0.0-win64\lib\clang\6.0.0\include" "${dir}\build\release\lib\LLVM-6.0.0-win64\lib\clang\6.0.0\"
         7z a -tzip "C:\projects\cquery\${dir}.zip" "${dir}"
       } Else {
         C:\msys64\usr\bin\bash -lc @'
@@ -45,5 +45,5 @@ artifacts:
   - path: 'cquery-*.zip'
 
 cache:
-  - C:\projects\cquery\build\LLVM-5.0.1-win64.exe
-  - C:\projects\cquery\build\LLVM-5.0.1-win64\
+  - C:\projects\cquery\build\LLVM-6.0.0-win64.exe
+  - C:\projects\cquery\build\LLVM-6.0.0-win64\
diff --git a/.travis.yml b/.travis.yml
index 0244a70d..c9ac2e61 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -26,8 +26,8 @@ os: linux
 
 cache:
   directories:
-    - build/clang+llvm-5.0.1-x86_64-linux-gnu-ubuntu-14.04/
-    - build/clang+llvm-5.0.1-x86_64-apple-darwin/
+    - build/clang+llvm-6.0.0-x86_64-linux-gnu-ubuntu-14.04/
+    - build/clang+llvm-6.0.0-x86_64-apple-darwin/
 
 matrix:
   fast_finish: true
diff --git a/src/platform_posix.cc b/src/platform_posix.cc
index 12cb4a37..18a11074 100644
--- a/src/platform_posix.cc
+++ b/src/platform_posix.cc
@@ -259,10 +259,6 @@ bool IsSymLink(const std::string& path) {
   return lstat(path.c_str(), &buf) == 0 && S_ISLNK(buf.st_mode);
 }
 
-std::vector<const char*> GetPlatformClangArguments() {
-  return {};
-}
-
 void FreeUnusedMemory() {
 #if defined(__GLIBC__)
   malloc_trim(0);
diff --git a/src/platform_win.cc b/src/platform_win.cc
index 87667d8d..726f964a 100644
--- a/src/platform_win.cc
+++ b/src/platform_win.cc
@@ -129,21 +129,6 @@ bool IsSymLink(const std::string& path) {
   return false;
 }
 
-std::vector<const char*> GetPlatformClangArguments() {
-  //
-  // Found by executing
-  //
-  //   $ clang++ -E -x c++ - -v
-  //
-  // https://clang.llvm.org/docs/MSVCCompatibility.html
-
-  // clang-format off
-  return {
-    "-fms-extensions", "-fms-compatibility", "-fdelayed-template-parsing"
-  };
-  // clang-format on
-}
-
 void FreeUnusedMemory() {}
 
 bool RunObjectiveCIndexTests() {
diff --git a/src/project.cc b/src/project.cc
index 3bec6f1a..35d86aab 100644
--- a/src/project.cc
+++ b/src/project.cc
@@ -27,8 +27,6 @@
 #include <unordered_set>
 #include <vector>
 
-extern bool gTestOutputMode;
-
 struct CompileCommandsEntry {
   std::string directory;
   std::string file;
@@ -195,12 +193,6 @@ Project::Entry GetCompilationEntryFromCompileCommandEntry(
   if (!AnyStartsWith(args, "-working-directory"))
     result.args.emplace_back("-working-directory=" + entry.directory);
 
-  if (!gTestOutputMode) {
-    std::vector<const char*> platform = GetPlatformClangArguments();
-    for (auto arg: platform)
-      result.args.push_back(arg);
-  }
-
   bool next_flag_is_path = false;
   bool add_next_flag_to_quote_dirs = false;
   bool add_next_flag_to_angle_dirs = false;