5 files changed, 1 insertions, 36 deletions
diff --git a/clang/lib/Driver/Job.cpp b/clang/lib/Driver/Job.cpp
index b494bc75282..765c05752d8 100644
--- a/clang/lib/Driver/Job.cpp
+++ b/clang/lib/Driver/Job.cpp
@@ -64,7 +64,7 @@ static bool skipArgs(const char *Flag, bool HaveCrashVFS, int &SkipNum,
     .Cases("-internal-externc-isystem", "-iprefix", true)
     .Cases("-iwithprefixbefore", "-isystem", "-iquote", true)
     .Cases("-isysroot", "-I", "-F", "-resource-dir", true)
-    .Cases("-iframework", "-include-pch", "-fsystem-include-if-exists", true)
+    .Cases("-iframework", "-include-pch", true)
     .Default(false);
   if (IsInclude)
     return HaveCrashVFS ? false : true;
diff --git a/clang/lib/Driver/ToolChains/Linux.cpp b/clang/lib/Driver/ToolChains/Linux.cpp
index 5ae250759b1..ca042f38db8 100644
--- a/clang/lib/Driver/ToolChains/Linux.cpp
+++ b/clang/lib/Driver/ToolChains/Linux.cpp
@@ -710,8 +710,6 @@ void Linux::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/include");
 
   addExternCSystemInclude(DriverArgs, CC1Args, SysRoot + "/usr/include");
-
-  AddGnuIncludeArgs(DriverArgs, CC1Args);
 }
 
 static std::string DetectLibcxxIncludePath(StringRef base) {
@@ -750,17 +748,6 @@ std::string Linux::findLibCxxIncludePath() const {
   return "";
 }
 
-void Linux::AddGnuIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                              llvm::opt::ArgStringList &CC1Args) const {
-  if (!DriverArgs.hasArg(options::OPT_ffreestanding)) {
-    // For gcc compatibility, clang will preinclude <stdc-predef.h>
-    // -ffreestanding suppresses this behavior.
-    CC1Args.push_back("-fsystem-include-if-exists");
-    CC1Args.push_back("stdc-predef.h");
-  }
-}
-
-
 void Linux::addLibStdCxxIncludePaths(const llvm::opt::ArgList &DriverArgs,
                                      llvm::opt::ArgStringList &CC1Args) const {
   // We need a detected GCC installation on Linux to provide libstdc++'s
diff --git a/clang/lib/Driver/ToolChains/Linux.h b/clang/lib/Driver/ToolChains/Linux.h
index 8b7e2e2ad53..9778c1832cc 100644
--- a/clang/lib/Driver/ToolChains/Linux.h
+++ b/clang/lib/Driver/ToolChains/Linux.h
@@ -31,8 +31,6 @@ public:
   void addLibStdCxxIncludePaths(
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
-  void AddGnuIncludeArgs(const llvm::opt::ArgList &DriverArgs,
-                          llvm::opt::ArgStringList &CC1Args) const;
   void AddCudaIncludeArgs(const llvm::opt::ArgList &DriverArgs,
                           llvm::opt::ArgStringList &CC1Args) const override;
   void AddIAMCUIncludeArgs(const llvm::opt::ArgList &DriverArgs,
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 748c7ffbcdf..384124bee2b 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2594,10 +2594,6 @@ static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
   for (const Arg *A : Args.filtered(OPT_chain_include))
     Opts.ChainedIncludes.emplace_back(A->getValue());
 
-  // Add the ordered list of -fsystem-include-if-exists.
-  for (const Arg *A : Args.filtered(OPT_fsystem_include_if_exists))
-    Opts.FSystemIncludeIfExists.emplace_back(A->getValue());
-
   for (const Arg *A : Args.filtered(OPT_remap_file)) {
     std::pair<StringRef, StringRef> Split = StringRef(A->getValue()).split(';');
 
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 6980706a90d..1dfbf187554 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -70,15 +70,6 @@ static void AddImplicitInclude(MacroBuilder &Builder, StringRef File) {
   Builder.append(Twine("#include \"") + File + "\"");
 }
 
-/// AddImplicitSystemIncludeIfExists - Add an implicit system \#include of the 
-/// specified file to the predefines buffer: precheck with __has_include.
-static void AddImplicitSystemIncludeIfExists(MacroBuilder &Builder, 
-                                             StringRef File) {
-  Builder.append(Twine("#if __has_include( <") + File + ">)");
-  Builder.append(Twine("#include <") + File + ">");
-  Builder.append(Twine("#endif"));
-}
-
 static void AddImplicitIncludeMacros(MacroBuilder &Builder, StringRef File) {
   Builder.append(Twine("#__include_macros \"") + File + "\"");
   // Marker token to stop the __include_macros fetch loop.
@@ -1119,13 +1110,6 @@ void clang::InitializePreprocessor(
   // Exit the command line and go back to <built-in> (2 is LC_LEAVE).
   if (!PP.getLangOpts().AsmPreprocessor)
     Builder.append("# 1 \"<built-in>\" 2");
-  
-  // Process -fsystem-include-if-exists directives.
-  for (unsigned i = 0, 
-       e = InitOpts.FSystemIncludeIfExists.size(); i != e; ++i) {
-    const std::string &Path = InitOpts.FSystemIncludeIfExists[i];
-    AddImplicitSystemIncludeIfExists(Builder, Path);
-  }
 
   // If -imacros are specified, include them now.  These are processed before
   // any -include directives.