diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1812,6 +1812,122 @@
   return Driver::GetResourcesPath(ClangExecutable, CLANG_RESOURCE_DIR);
 }
 
+static void GenerateHeaderSearchArgs(const HeaderSearchOptions &Opts,
+                                     SmallVectorImpl<const char *> &Args,
+                                     CompilerInvocation::StringAllocator SA) {
+  const OptTable &OptTable = getDriverOptTable();
+
+  std::string Dash("-");
+  std::string OptName;
+
+  if (Opts.UseLibcxx) {
+    OptName = Dash + OptTable.getOptionName(OPT_stdlib_EQ);
+    Args.emplace_back(SA(OptName + "libc++"));
+  }
+
+  if (!Opts.ModuleCachePath.empty()) {
+    OptName = Dash + OptTable.getOptionName(OPT_fmodules_cache_path);
+    Args.emplace_back(SA(OptName + Opts.ModuleCachePath));
+  }
+
+  OptName = Dash + OptTable.getOptionName(OPT_fmodule_file);
+  for (const auto &File : Opts.PrebuiltModuleFiles)
+    Args.emplace_back(SA(OptName + File.first + "=" + File.second));
+
+  OptName = Dash + OptTable.getOptionName(OPT_fprebuilt_module_path);
+  for (const auto &Path : Opts.PrebuiltModulePaths)
+    Args.emplace_back(SA(OptName + Path));
+
+  OptName = Dash + OptTable.getOptionName(OPT_fmodules_ignore_macro);
+  for (const auto &Macro : Opts.ModulesIgnoreMacros)
+    Args.emplace_back(SA(OptName + Macro.val()));
+
+  auto matches = [](const HeaderSearchOptions::Entry &Entry,
+                    frontend::IncludeDirGroup Group, bool IsFramework,
+                    bool IgnoreSysRoot) {
+    return Entry.Group == Group && Entry.IsFramework == IsFramework &&
+           Entry.IgnoreSysRoot == IgnoreSysRoot;
+  };
+
+  for (const HeaderSearchOptions::Entry &E : Opts.UserEntries) {
+    Optional<OptSpecifier> Opt;
+
+    // Add -I..., -F..., and -index-header-map options in order.
+
+    if (E.Group == frontend::IndexHeaderMap) {
+      OptName = OptTable.getOptionName(OPT_index_header_map);
+      Args.emplace_back(SA(OptName));
+    }
+
+    if (matches(E, frontend::IndexHeaderMap, true, true))
+      Opt = OPT_F;
+    else if (matches(E, frontend::IndexHeaderMap, false, true))
+      Opt = OPT_I;
+    else if (matches(E, frontend::Angled, true, true))
+      Opt = OPT_F;
+    else if (matches(E, frontend::Angled, false, true))
+      // Also handles [-iprefix=xx] -iwithprefixbefore=yy as -I[xx]yy.
+      Opt = OPT_I;
+
+    if (Opt) {
+      OptName = Dash + OptTable.getOptionName(*Opt);
+      Args.emplace_back(SA(OptName + E.Path));
+      continue;
+    }
+
+    if (matches(E, frontend::After, false, true))
+      // Also handles [-iprefix=xx] -iwithprefix=yy as -idirafter=[xx]yy.
+      Opt = OPT_idirafter;
+    else if (matches(E, frontend::Quoted, false, true))
+      Opt = OPT_iquote;
+    else if (matches(E, frontend::System, false, true))
+      Opt = OPT_isystem;
+    else if (matches(E, frontend::System, false, false))
+      Opt = OPT_iwithsysroot;
+    else if (matches(E, frontend::System, true, true))
+      Opt = OPT_iframework;
+    else if (matches(E, frontend::System, true, false))
+      Opt = OPT_iframeworkwithsysroot;
+
+    else if (matches(E, frontend::CSystem, false, true))
+      // Add the paths for the various language specific isystem flags.
+      Opt = OPT_c_isystem;
+    else if (matches(E, frontend::CXXSystem, false, true))
+      Opt = OPT_cxx_isystem;
+    else if (matches(E, frontend::ObjCSystem, false, true))
+      Opt = OPT_objc_isystem;
+    else if (matches(E, frontend::ObjCXXSystem, false, true))
+      Opt = OPT_objcxx_isystem;
+
+    else if (matches(E, frontend::System, false, true))
+      // Add the internal paths from a driver that detects standard include
+      // paths.
+      Opt = OPT_internal_isystem;
+    else if (matches(E, frontend::ExternCSystem, false, true))
+      Opt = OPT_internal_externc_isystem;
+    else
+      llvm_unreachable("Tried to marshall invalid HeaderSearchOptions::Entry");
+
+    OptName = Dash + OptTable.getOptionName(*Opt);
+    Args.emplace_back(SA(OptName));
+    Args.emplace_back(SA(E.Path));
+  }
+
+  // Add the path prefixes which are implicitly treated as being system headers.
+  for (const auto &P : Opts.SystemHeaderPrefixes) {
+    OptSpecifier Opt = P.IsSystemHeader ? OPT_system_header_prefix
+                                        : OPT_no_system_header_prefix;
+    OptName = Dash + Dash + OptTable.getOptionName(Opt);
+    Args.emplace_back(SA(OptName + P.Prefix));
+  }
+
+  for (const std::string &F : Opts.VFSOverlayFiles) {
+    OptName = Dash + OptTable.getOptionName(OPT_ivfsoverlay);
+    Args.emplace_back(SA(OptName));
+    Args.emplace_back(F.c_str());
+  }
+}
+
 static void ParseHeaderSearchArgs(HeaderSearchOptions &Opts, ArgList &Args,
                                   const std::string &WorkingDir) {
   if (const Arg *A = Args.getLastArg(OPT_stdlib_EQ))
@@ -3215,6 +3331,8 @@
 #undef DIAG_OPTION_WITH_MARSHALLING
 #undef OPTION_WITH_MARSHALLING
 #undef GENERATE_OPTION_WITH_MARSHALLING
+
+  GenerateHeaderSearchArgs(getHeaderSearchOpts(), Args, SA);
 }
 
 IntrusiveRefCntPtr<llvm::vfs::FileSystem>