diff --git a/src/clang_tu.cc b/src/clang_tu.cc
index 9e026652..23e41f16 100644
--- a/src/clang_tu.cc
+++ b/src/clang_tu.cc
@@ -96,9 +96,10 @@ Range fromTokenRangeDefaulted(const SourceManager &sm, const LangOptions &lang,
 
 std::unique_ptr<CompilerInvocation>
 buildCompilerInvocation(const std::string &main, std::vector<const char *> args,
-                        IntrusiveRefCntPtr<llvm::vfs::FileSystem> vfs) {
+                        IntrusiveRefCntPtr<llvm::vfs::FileSystem> vfs,
+                        const std::string &working_dir) {
   std::string save = "-resource-dir=" + g_config->clang.resourceDir;
-  args.push_back(save.c_str());
+  args.push_back(intern(save));
   args.push_back("-fsyntax-only");
 
   // Similar to clang/tools/driver/driver.cpp:insertTargetAndModeArgs but don't
@@ -146,12 +147,14 @@ buildCompilerInvocation(const std::string &main, std::vector<const char *> args,
   if (StringRef(cmd.getCreator().getName()) != "clang")
     return nullptr;
   const llvm::opt::ArgStringList &cc_args = cmd.getArguments();
+  auto c_args = const_cast<llvm::opt::ArgStringList *>(&cc_args);
+  c_args->append({intern("-working-directory=" + working_dir)});
   auto ci = std::make_unique<CompilerInvocation>();
 #if LLVM_VERSION_MAJOR >= 10 // rC370122
-  if (!CompilerInvocation::CreateFromArgs(*ci, cc_args, *diags))
+  if (!CompilerInvocation::CreateFromArgs(*ci, *c_args, *diags))
 #else
   if (!CompilerInvocation::CreateFromArgs(
-          *ci, cc_args.data(), cc_args.data() + cc_args.size(), *diags))
+          *ci, c_args->data(), c_args->data() + c_args->size(), *diags))
 #endif
     return nullptr;
 
diff --git a/src/clang_tu.hh b/src/clang_tu.hh
index 7dbfc4a8..7b696346 100644
--- a/src/clang_tu.hh
+++ b/src/clang_tu.hh
@@ -42,7 +42,8 @@ Range fromTokenRangeDefaulted(const clang::SourceManager &sm,
 
 std::unique_ptr<clang::CompilerInvocation>
 buildCompilerInvocation(const std::string &main, std::vector<const char *> args,
-                        llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS);
+                        llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
+                        const std::string &working_dir);
 
 const char *clangBuiltinTypeName(int);
 } // namespace ccls
diff --git a/src/indexer.cc b/src/indexer.cc
index 644c0ccb..3ff1629a 100644
--- a/src/indexer.cc
+++ b/src/indexer.cc
@@ -1277,7 +1277,7 @@ index(SemaManager *manager, WorkingFiles *wfiles, VFS *vfs,
   llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> fs =
       llvm::vfs::getRealFileSystem();
   std::shared_ptr<CompilerInvocation> ci =
-      buildCompilerInvocation(main, args, fs);
+      buildCompilerInvocation(main, args, fs, opt_wdir);
   // e.g. .s
   if (!ci)
     return {};
diff --git a/src/query.hh b/src/query.hh
index cd3a19c1..3b033a9e 100644
--- a/src/query.hh
+++ b/src/query.hh
@@ -10,6 +10,7 @@
 #include <llvm/ADT/DenseMap.h>
 #include <llvm/ADT/SmallVector.h>
 #include <llvm/ADT/StringMap.h>
+#include <llvm/ADT/STLExtras.h>
 
 namespace llvm {
 template <> struct DenseMapInfo<ccls::ExtentRef> {
diff --git a/src/sema_manager.cc b/src/sema_manager.cc
index dbe57672..39e21843 100644
--- a/src/sema_manager.cc
+++ b/src/sema_manager.cc
@@ -433,8 +433,8 @@ void *preambleMain(void *manager_) {
     auto stat_cache = std::make_unique<PreambleStatCache>();
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> fs =
         stat_cache->producer(session->fs);
-    if (std::unique_ptr<CompilerInvocation> ci =
-            buildCompilerInvocation(task.path, session->file.args, fs))
+    if (std::unique_ptr<CompilerInvocation> ci = buildCompilerInvocation(
+            task.path, session->file.args, fs, session->file.directory))
       buildPreamble(*session, *ci, fs, task, std::move(stat_cache));
 
     if (task.comp_task) {
@@ -475,8 +475,8 @@ void *completionMain(void *manager_) {
     std::shared_ptr<PreambleData> preamble = session->getPreamble();
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> fs =
         preamble ? preamble->stat_cache->consumer(session->fs) : session->fs;
-    std::unique_ptr<CompilerInvocation> ci =
-        buildCompilerInvocation(task->path, session->file.args, fs);
+    std::unique_ptr<CompilerInvocation> ci = buildCompilerInvocation(
+        task->path, session->file.args, fs, session->file.directory);
     if (!ci)
       continue;
     auto &fOpts = ci->getFrontendOpts();
@@ -569,8 +569,8 @@ void *diagnosticMain(void *manager_) {
     std::shared_ptr<PreambleData> preamble = session->getPreamble();
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> fs =
         preamble ? preamble->stat_cache->consumer(session->fs) : session->fs;
-    std::unique_ptr<CompilerInvocation> ci =
-        buildCompilerInvocation(task.path, session->file.args, fs);
+    std::unique_ptr<CompilerInvocation> ci = buildCompilerInvocation(
+        task.path, session->file.args, fs, session->file.directory);
     if (!ci)
       continue;
     if (preamble) {