diff --git a/CMakeLists.txt b/CMakeLists.txt
index 49a3061a..2e829ca7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -193,7 +193,7 @@ target_sources(ccls PRIVATE
                src/clang_tu.cc
                src/clang_utils.cc
                src/config.cc
-               src/diagnostics_engine.cc
+               src/diagnostics_publisher.cc
                src/file_consumer.cc
                src/filesystem.cc
                src/fuzzy_match.cc
diff --git a/cmake/FindClang.cmake b/cmake/FindClang.cmake
index 6bfac108..4fd60949 100644
--- a/cmake/FindClang.cmake
+++ b/cmake/FindClang.cmake
@@ -69,6 +69,8 @@ set(_Clang_REQUIRED_VARS Clang_LIBRARY Clang_INCLUDE_DIR Clang_EXECUTABLE
                          LLVM_INCLUDE_DIR LLVM_BUILD_INCLUDE_DIR)
 
 _Clang_find_library(Clang_LIBRARY clang)
+_Clang_find_add_library(clangFrontend)
+_Clang_find_add_library(clangSerialization)
 _Clang_find_add_library(clangAST)
 _Clang_find_add_library(clangLex)
 _Clang_find_add_library(clangDriver)
@@ -76,9 +78,11 @@ _Clang_find_add_library(clangBasic)
 if(USE_SHARED_LLVM)
   _Clang_find_add_library(LLVM)
 else()
+  _Clang_find_add_library(LLVMBitReader)
+  _Clang_find_add_library(LLVMOption)
+  _Clang_find_add_library(LLVMProfileData)
   _Clang_find_add_library(LLVMCore)
   _Clang_find_add_library(LLVMBinaryFormat)
-  _Clang_find_add_library(LLVMOption)
   _Clang_find_add_library(LLVMSupport)
   _Clang_find_add_library(LLVMDemangle)
 endif()
diff --git a/src/diagnostics_engine.cc b/src/diagnostics_publisher.cc
similarity index 79%
rename from src/diagnostics_engine.cc
rename to src/diagnostics_publisher.cc
index c714ec9b..6402d98c 100644
--- a/src/diagnostics_engine.cc
+++ b/src/diagnostics_publisher.cc
@@ -1,19 +1,19 @@
-#include "diagnostics_engine.h"
+#include "diagnostics_publisher.hh"
 
 #include "pipeline.hh"
 using namespace ccls;
 
 #include <chrono>
 
-void DiagnosticsEngine::Init() {
+void DiagnosticsPublisher::Init() {
   frequencyMs_ = g_config->diagnostics.frequencyMs;
   match_ = std::make_unique<GroupMatch>(g_config->diagnostics.whitelist,
                                         g_config->diagnostics.blacklist);
 }
 
-void DiagnosticsEngine::Publish(WorkingFiles* working_files,
-                                std::string path,
-                                std::vector<lsDiagnostic> diagnostics) {
+void DiagnosticsPublisher::Publish(WorkingFiles* working_files,
+                                   std::string path,
+                                   std::vector<lsDiagnostic> diagnostics) {
   // Cache diagnostics so we can show fixits.
   working_files->DoActionOnFile(path, [&](WorkingFile* working_file) {
     if (working_file)
diff --git a/src/diagnostics_engine.h b/src/diagnostics_publisher.hh
similarity index 91%
rename from src/diagnostics_engine.h
rename to src/diagnostics_publisher.hh
index 2d3e7aee..a6b5a688 100644
--- a/src/diagnostics_engine.h
+++ b/src/diagnostics_publisher.hh
@@ -3,7 +3,7 @@
 #include "match.h"
 #include "working_files.h"
 
-class DiagnosticsEngine {
+class DiagnosticsPublisher {
   std::unique_ptr<GroupMatch> match_;
   int64_t nextPublish_ = 0;
   int frequencyMs_;
diff --git a/src/indexer.cc b/src/indexer.cc
index 3777bfd6..d8fd7ad9 100644
--- a/src/indexer.cc
+++ b/src/indexer.cc
@@ -2070,9 +2070,6 @@ std::vector<std::unique_ptr<IndexFile>> ParseWithTu(
     const std::string& file,
     const std::vector<std::string>& args,
     const std::vector<CXUnsavedFile>& file_contents) {
-  Timer timer;
-  timer.startTimer();
-
   IndexerCallbacks callback = {0};
   // Available callbacks:
   // - abortQuery
@@ -2114,8 +2111,6 @@ std::vector<std::unique_ptr<IndexFile>> ParseWithTu(
   ClangCursor(clang_getTranslationUnitCursor(tu->cx_tu))
       .VisitChildren(&VisitMacroDefinitionAndExpansions, &param);
 
-  timer.stopTimer();
-
   std::unordered_map<std::string, int> inc_to_line;
   // TODO
   if (param.primary_file)
diff --git a/src/message_handler.h b/src/message_handler.h
index 64e73e57..58bb1329 100644
--- a/src/message_handler.h
+++ b/src/message_handler.h
@@ -14,7 +14,7 @@
 struct ClangCompleteManager;
 struct CodeCompleteCache;
 struct Config;
-class DiagnosticsEngine;
+class DiagnosticsPublisher;
 struct VFS;
 struct ImportManager;
 struct IncludeComplete;
@@ -104,7 +104,7 @@ struct MessageHandler {
   DB* db = nullptr;
   MultiQueueWaiter* waiter = nullptr;
   Project* project = nullptr;
-  DiagnosticsEngine* diag_engine = nullptr;
+  DiagnosticsPublisher* diag_pub = nullptr;
   VFS* vfs = nullptr;
   ImportManager* import_manager = nullptr;
   SemanticHighlightSymbolCache* semantic_cache = nullptr;
diff --git a/src/messages/initialize.cc b/src/messages/initialize.cc
index 02d6c1db..55d8a2e6 100644
--- a/src/messages/initialize.cc
+++ b/src/messages/initialize.cc
@@ -1,4 +1,4 @@
-#include "diagnostics_engine.h"
+#include "diagnostics_publisher.hh"
 #include "filesystem.hh"
 #include "include_complete.h"
 #include "log.hh"
@@ -492,7 +492,7 @@ struct Handler_Initialize : BaseMessageHandler<In_InitializeRequest> {
     sys::fs::create_directories(g_config->cacheDirectory + '@' +
                                 EscapeFileName(g_config->projectRoot));
 
-    diag_engine->Init();
+    diag_pub->Init();
     semantic_cache->Init();
 
     // Open up / load the project.
@@ -510,7 +510,7 @@ struct Handler_Initialize : BaseMessageHandler<In_InitializeRequest> {
         g_thread_id = i + 1;
         std::string name = "indexer" + std::to_string(i);
         set_thread_name(name.c_str());
-        pipeline::Indexer_Main(diag_engine, vfs, project, working_files);
+        pipeline::Indexer_Main(diag_pub, vfs, project, working_files);
       }).detach();
     }
 
diff --git a/src/pipeline.cc b/src/pipeline.cc
index cece67d3..52d154f7 100644
--- a/src/pipeline.cc
+++ b/src/pipeline.cc
@@ -2,7 +2,7 @@
 
 #include "clang_complete.h"
 #include "config.h"
-#include "diagnostics_engine.h"
+#include "diagnostics_publisher.hh"
 #include "include_complete.h"
 #include "log.hh"
 #include "lsp.h"
@@ -119,7 +119,7 @@ std::unique_ptr<IndexFile> RawCacheLoad(
                      *file_content, IndexFile::kMajorVersion);
 }
 
-bool Indexer_Parse(DiagnosticsEngine* diag_engine,
+bool Indexer_Parse(DiagnosticsPublisher* diag_pub,
                    WorkingFiles* working_files,
                    Project* project,
                    VFS* vfs,
@@ -224,7 +224,7 @@ bool Indexer_Parse(DiagnosticsEngine* diag_engine,
     // to identify indexing problems. For interactive sessions, diagnostics are
     // handled by code completion.
     if (!request.is_interactive)
-      diag_engine->Publish(working_files, curr->path, curr->diagnostics_);
+      diag_pub->Publish(working_files, curr->path, curr->diagnostics_);
 
     std::string path = curr->path;
     if (!(vfs->Stamp(path, curr->last_write_time) || path == path_to_index))
@@ -275,7 +275,7 @@ void Init() {
   for_stdout = new ThreadedQueue<Stdout_Request>(stdout_waiter);
 }
 
-void Indexer_Main(DiagnosticsEngine* diag_engine,
+void Indexer_Main(DiagnosticsPublisher* diag_pub,
                   VFS* vfs,
                   Project* project,
                   WorkingFiles* working_files) {
@@ -283,7 +283,7 @@ void Indexer_Main(DiagnosticsEngine* diag_engine,
   ClangIndexer indexer;
 
   while (true)
-    if (!Indexer_Parse(diag_engine, working_files, project, vfs, &indexer))
+    if (!Indexer_Parse(diag_pub, working_files, project, vfs, &indexer))
       indexer_waiter->Wait(index_request);
 }
 
@@ -386,12 +386,12 @@ void MainLoop() {
   SemanticHighlightSymbolCache semantic_cache;
   WorkingFiles working_files;
   VFS vfs;
-  DiagnosticsEngine diag_engine;
+  DiagnosticsPublisher diag_pub;
 
   ClangCompleteManager clang_complete(
       &project, &working_files,
       [&](std::string path, std::vector<lsDiagnostic> diagnostics) {
-        diag_engine.Publish(&working_files, path, diagnostics);
+        diag_pub.Publish(&working_files, path, diagnostics);
       },
       [](lsRequestId id) {
         if (id.Valid()) {
@@ -416,7 +416,7 @@ void MainLoop() {
     handler->db = &db;
     handler->waiter = indexer_waiter;
     handler->project = &project;
-    handler->diag_engine = &diag_engine;
+    handler->diag_pub = &diag_pub;
     handler->vfs = &vfs;
     handler->semantic_cache = &semantic_cache;
     handler->working_files = &working_files;
diff --git a/src/pipeline.hh b/src/pipeline.hh
index f21a44c7..a3926594 100644
--- a/src/pipeline.hh
+++ b/src/pipeline.hh
@@ -7,7 +7,7 @@
 #include <unordered_map>
 #include <vector>
 
-class DiagnosticsEngine;
+class DiagnosticsPublisher;
 struct VFS;
 struct Project;
 struct WorkingFiles;
@@ -18,7 +18,7 @@ namespace ccls::pipeline {
 void Init();
 void LaunchStdin();
 void LaunchStdout();
-void Indexer_Main(DiagnosticsEngine* diag_engine,
+void Indexer_Main(DiagnosticsPublisher* diag_pub,
                   VFS* vfs,
                   Project* project,
                   WorkingFiles* working_files);
diff --git a/src/project.cc b/src/project.cc
index 1310efc1..4c7bf737 100644
--- a/src/project.cc
+++ b/src/project.cc
@@ -12,7 +12,10 @@
 #include "working_files.h"
 using namespace ccls;
 
+#include <clang/Driver/Compilation.h>
+#include <clang/Driver/Driver.h>
 #include <clang/Driver/Options.h>
+#include <clang/Frontend/CompilerInstance.h>
 #include <llvm/ADT/ArrayRef.h>
 #include <llvm/Option/ArgList.h>
 #include <llvm/Option/OptTable.h>
@@ -97,6 +100,7 @@ Project::Entry GetCompilationEntryFromCompileCommandEntry(
   args.insert(args.end(), config->extra_flags.begin(),
               config->extra_flags.end());
 
+#if 1
   std::unique_ptr<OptTable> Opts = driver::createDriverOptTable();
   unsigned MissingArgIndex, MissingArgCount;
   std::vector<const char*> cargs;
@@ -105,18 +109,63 @@ Project::Entry GetCompilationEntryFromCompileCommandEntry(
   InputArgList Args =
       Opts->ParseArgs(makeArrayRef(cargs), MissingArgIndex, MissingArgCount,
                       driver::options::CC1Option);
-
   using namespace clang::driver::options;
-  for (const auto* A :
-       Args.filtered(OPT_I, OPT_c_isystem, OPT_cxx_isystem, OPT_isystem))
+  for (const auto* A : Args.filtered(OPT_I, OPT_c_isystem, OPT_cxx_isystem,
+                                     OPT_isystem, OPT_idirafter))
     config->angle_dirs.insert(entry.ResolveIfRelative(A->getValue()));
   for (const auto* A : Args.filtered(OPT_I, OPT_iquote))
     config->quote_dirs.insert(entry.ResolveIfRelative(A->getValue()));
-  for (const auto* A : Args.filtered(OPT_idirafter)) {
-    std::string dir = entry.ResolveIfRelative(A->getValue());
-    config->angle_dirs.insert(dir);
-    config->quote_dirs.insert(dir);
+#else
+  // a weird C++ deduction guide heap-use-after-free causes libclang to crash.
+  IgnoringDiagConsumer DiagC;
+  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts(new DiagnosticOptions());
+  DiagnosticsEngine Diags(
+      IntrusiveRefCntPtr<DiagnosticIDs>(new DiagnosticIDs()), &*DiagOpts,
+      &DiagC, false);
+
+  driver::Driver Driver(args[0], llvm::sys::getDefaultTargetTriple(), Diags);
+  auto TargetAndMode =
+      driver::ToolChain::getTargetAndModeFromProgramName(args[0]);
+  if (!TargetAndMode.TargetPrefix.empty()) {
+    const char* arr[] = {"-target", TargetAndMode.TargetPrefix.c_str()};
+    args.insert(args.begin() + 1, std::begin(arr), std::end(arr));
+    Driver.setTargetAndMode(TargetAndMode);
   }
+  Driver.setCheckInputsExist(false);
+
+  std::vector<const char*> cargs;
+  for (auto& arg : args)
+    cargs.push_back(arg.c_str());
+  cargs.push_back("-fsyntax-only");
+  std::unique_ptr<driver::Compilation> C(Driver.BuildCompilation(cargs));
+  const driver::JobList& Jobs = C->getJobs();
+  if (Jobs.size() != 1)
+    return result;
+  const driver::ArgStringList& CCArgs = Jobs.begin()->getArguments();
+
+  auto Invocation = std::make_unique<CompilerInvocation>();
+  CompilerInvocation::CreateFromArgs(*Invocation, CCArgs.data(),
+                                     CCArgs.data() + CCArgs.size(), Diags);
+  Invocation->getFrontendOpts().DisableFree = false;
+  Invocation->getCodeGenOpts().DisableFree = false;
+
+  HeaderSearchOptions& HeaderOpts = Invocation->getHeaderSearchOpts();
+  for (auto& E : HeaderOpts.UserEntries) {
+    std::string path = entry.ResolveIfRelative(E.Path);
+    switch (E.Group) {
+      default:
+        config->angle_dirs.insert(path);
+        break;
+      case frontend::Quoted:
+        config->quote_dirs.insert(path);
+        break;
+      case frontend::Angled:
+        config->angle_dirs.insert(path);
+        config->quote_dirs.insert(path);
+        break;
+    }
+  }
+#endif
 
   for (size_t i = 1; i < args.size(); i++)
     // This is most likely the file path we will be passing to clang. The
@@ -128,9 +177,9 @@ Project::Entry GetCompilationEntryFromCompileCommandEntry(
       continue;
     }
 
-  if (!Args.hasArg(OPT_resource_dir))
+  // if (HeaderOpts.ResourceDir.empty() && HeaderOpts.UseBuiltinIncludes)
     args.push_back("-resource-dir=" + g_config->clang.resourceDir);
-  if (!Args.hasArg(OPT_working_directory))
+  // if (Invocation->getFileSystemOpts().WorkingDir.empty())
     args.push_back("-working-directory=" + entry.directory);
 
   // There could be a clang version mismatch between what the project uses and