diff --git a/src/filesystem.cc b/src/filesystem.cc
index c433dae0..dad07ddd 100644
--- a/src/filesystem.cc
+++ b/src/filesystem.cc
@@ -31,7 +31,8 @@ void getFilesInFolder(std::string folder, bool recursive, bool dir_prefix,
       curr.pop_back();
       for (sys::fs::directory_iterator i(folder1, ec, false), e; i != e && !ec;
            i.increment(ec)) {
-        std::string path = i->path(), filename = sys::path::filename(path);
+        std::string path = i->path();
+        std::string filename(sys::path::filename(path));
         if ((filename[0] == '.' && filename != ".ccls") ||
             sys::fs::status(path, status, false))
           continue;
diff --git a/src/indexer.cc b/src/indexer.cc
index a281e54b..014a7e8b 100644
--- a/src/indexer.cc
+++ b/src/indexer.cc
@@ -504,7 +504,7 @@ public:
     llvm::raw_svector_ostream os(str);
     d->print(os, getDefaultPolicy());
 
-    std::string name = os.str();
+    std::string name(str.data(), str.size());
     simplifyAnonymous(name);
     // Remove \n in DeclPrinter.cpp "{\n" + if(!TerseOutput)something + "}"
     for (std::string::size_type i = 0;;) {
diff --git a/src/main.cc b/src/main.cc
index 93f9d3b7..eb18d26c 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -134,7 +134,7 @@ int main(int argc, char **argv) {
     if (opt_index.size()) {
       SmallString<256> root(opt_index);
       sys::fs::make_absolute(root);
-      pipeline::standalone(root.str());
+      pipeline::standalone(std::string(root.data(), root.size()));
     } else {
       // The thread that reads from stdin and dispatchs commands to the main
       // thread.
diff --git a/src/pipeline.cc b/src/pipeline.cc
index 107ca4a1..4773c69b 100644
--- a/src/pipeline.cc
+++ b/src/pipeline.cc
@@ -113,7 +113,7 @@ bool cacheInvalid(VFS *vfs, IndexFile *prev, const std::string &path,
   }
 
   // For inferred files, allow -o a a.cc -> -o b b.cc
-  std::string stem = sys::path::stem(path);
+  StringRef stem = sys::path::stem(path);
   int changed = -1, size = std::min(prev->args.size(), args.size());
   for (int i = 0; i < size; i++)
     if (strcmp(prev->args[i], args[i]) && sys::path::stem(args[i]) != stem) {
diff --git a/src/platform.hh b/src/platform.hh
index 5fa7cfe7..ecb6326d 100644
--- a/src/platform.hh
+++ b/src/platform.hh
@@ -1,14 +1,14 @@
-// Copyright 2017-2018 ccls Authors
+// Copyright 2017-2020 ccls Authors
 // SPDX-License-Identifier: Apache-2.0
 
 #pragma once
 
+#include <llvm/ADT/StringRef.h>
+
 #include <string>
-#include <string_view>
-#include <vector>
 
 namespace ccls {
-std::string normalizePath(const std::string &path);
+std::string normalizePath(llvm::StringRef path);
 
 // Free any unused memory and return it to the system.
 void freeUnusedMemory();
diff --git a/src/platform_posix.cc b/src/platform_posix.cc
index 6fd04995..5a937c65 100644
--- a/src/platform_posix.cc
+++ b/src/platform_posix.cc
@@ -40,7 +40,7 @@ namespace pipeline {
 void threadEnter();
 }
 
-std::string normalizePath(const std::string &path) {
+std::string normalizePath(llvm::StringRef path) {
   llvm::SmallString<256> p(path);
   llvm::sys::path::remove_dots(p, true);
   return {p.data(), p.size()};
diff --git a/src/platform_win.cc b/src/platform_win.cc
index 9fa28e3b..4cafb3d7 100644
--- a/src/platform_win.cc
+++ b/src/platform_win.cc
@@ -19,17 +19,12 @@
 #include <thread>
 
 namespace ccls {
-std::string normalizePath(const std::string &path) {
-  DWORD retval = 0;
+std::string normalizePath(llvm::StringRef path) {
   TCHAR buffer[MAX_PATH] = TEXT("");
   TCHAR **lpp_part = {NULL};
 
-  std::string result;
-  retval = GetFullPathName(path.c_str(), MAX_PATH, buffer, lpp_part);
-  // fail, return original
-  if (retval == 0)
-    result = path;
-  else
+  std::string result(path);
+  if (GetFullPathName(result.c_str(), MAX_PATH, buffer, lpp_part) != 0)
     result = buffer;
 
   std::replace(result.begin(), result.end(), '\\', '/');
diff --git a/src/project.cc b/src/project.cc
index 54a56f23..0761f291 100644
--- a/src/project.cc
+++ b/src/project.cc
@@ -222,7 +222,7 @@ readCompilerArgumentsFromFile(const std::string &path) {
     return {};
   std::vector<const char *> args;
   for (line_iterator i(*mbOrErr.get(), true, '#'), e; i != e; ++i) {
-    std::string line = *i;
+    std::string line(*i);
     doPathMapping(line);
     args.push_back(intern(line));
   }
@@ -632,7 +632,7 @@ void Project::index(WorkingFiles *wfiles, RequestId id) {
 void Project::indexRelated(const std::string &path) {
   auto &gi = g_config->index;
   GroupMatch match(gi.whitelist, gi.blacklist);
-  std::string stem = sys::path::stem(path);
+  StringRef stem = sys::path::stem(path);
   std::vector<const char *> args, extra_args;
   for (const std::string &arg : g_config->clang.extraArgs)
     extra_args.push_back(intern(arg));
diff --git a/src/sema_manager.cc b/src/sema_manager.cc
index 8bc8db83..d97875e6 100644
--- a/src/sema_manager.cc
+++ b/src/sema_manager.cc
@@ -623,9 +623,10 @@ void *diagnosticMain(void *manager_) {
         for (const Note &n : d.notes) {
           SmallString<256> str(n.file);
           llvm::sys::path::remove_dots(str, true);
-          Location loc{DocumentUri::fromPath(str.str()),
-                       lsRange{{n.range.start.line, n.range.start.column},
-                               {n.range.end.line, n.range.end.column}}};
+          Location loc{
+              DocumentUri::fromPath(std::string(str.data(), str.size())),
+              lsRange{{n.range.start.line, n.range.start.column},
+                      {n.range.end.line, n.range.end.column}}};
           ls_diag.relatedInformation.push_back({loc, n.message});
         }
       } else {
diff --git a/src/serializer.cc b/src/serializer.cc
index 6d878ac4..99cea067 100644
--- a/src/serializer.cc
+++ b/src/serializer.cc
@@ -217,7 +217,7 @@ void reflect(JsonWriter &vis, IndexInclude &v) {
   reflectMemberStart(vis);
   REFLECT_MEMBER(line);
   if (gTestOutputMode) {
-    std::string basename = llvm::sys::path::filename(v.resolved_path);
+    std::string basename(llvm::sys::path::filename(v.resolved_path));
     if (v.resolved_path[0] != '&')
       basename = "&" + basename;
     REFLECT_MEMBER2("resolved_path", basename);