diff --git a/cmake/FindClang.cmake b/cmake/FindClang.cmake
index cc808ccc..ad085d48 100644
--- a/cmake/FindClang.cmake
+++ b/cmake/FindClang.cmake
@@ -118,5 +118,6 @@ if(Clang_FOUND AND NOT TARGET Clang::Clang)
     INTERFACE_INCLUDE_DIRECTORIES "${Clang_INCLUDE_DIR};${Clang_BUILD_INCLUDE_DIR};${LLVM_INCLUDE_DIR};${LLVM_BUILD_INCLUDE_DIR}")
 
   find_package(Curses REQUIRED)
-  set_property(TARGET Clang::Clang PROPERTY IMPORTED_LINK_INTERFACE_LIBRARIES "${_Clang_LIBRARIES};${CURSES_LIBRARIES}")
+  find_package(ZLIB REQUIRED)
+  set_property(TARGET Clang::Clang PROPERTY IMPORTED_LINK_INTERFACE_LIBRARIES "${_Clang_LIBRARIES};${CURSES_LIBRARIES};${ZLIB_LIBRARIES}")
 endif()
diff --git a/src/import_pipeline.cc b/src/import_pipeline.cc
index 625ba878..5ed8ebd8 100644
--- a/src/import_pipeline.cc
+++ b/src/import_pipeline.cc
@@ -115,11 +115,11 @@ bool Indexer_Parse(DiagnosticsEngine* diag_engine,
                        path_to_index, entry.args, std::nullopt))
       reparse = 2;
     for (const auto& dep : prev->dependencies)
-      if (auto write_time1 = LastWriteTime(dep.first)) {
+      if (auto write_time1 = LastWriteTime(dep.first().str())) {
         if (dep.second < *write_time1) {
           reparse = 2;
           std::lock_guard<std::mutex> lock(vfs->mutex);
-          vfs->state[dep.first].stage = 0;
+          vfs->state[dep.first().str()].stage = 0;
         }
       } else
         reparse = 2;
@@ -134,8 +134,8 @@ bool Indexer_Parse(DiagnosticsEngine* diag_engine,
         request.is_interactive);
     }
     for (const auto& dep : dependencies)
-      if (vfs->Mark(dep.first, 0, 2)) {
-        prev = cache.RawCacheLoad(dep.first);
+      if (vfs->Mark(dep.first().str(), 0, 2)) {
+        prev = cache.RawCacheLoad(dep.first().str());
         IndexUpdate update = IndexUpdate::CreateDelta(nullptr, prev.get());
         queue->on_indexed.PushBack(Index_OnIndexed(std::move(update), perf),
           request.is_interactive);
@@ -189,7 +189,7 @@ bool Indexer_Parse(DiagnosticsEngine* diag_engine,
     if (entry.id >= 0) {
       std::lock_guard<std::mutex> lock(project->mutex_);
       for (auto& dep : curr->dependencies)
-        project->absolute_path_to_entry_index_[dep.first] = entry.id;
+        project->absolute_path_to_entry_index_[dep.first()] = entry.id;
     }
 
     // Build delta update.
@@ -388,7 +388,6 @@ void MainLoop(MultiQueueWaiter* querydb_waiter,
   }
 
   // Run query db main loop.
-  SetThreadName("querydb");
   auto* queue = QueueManager::instance();
   while (true) {
     std::vector<std::unique_ptr<InMessage>> messages =
diff --git a/src/indexer.h b/src/indexer.h
index 12bed98c..55dc00e8 100644
--- a/src/indexer.h
+++ b/src/indexer.h
@@ -13,6 +13,8 @@
 #include "symbol.h"
 #include "utils.h"
 
+#include <llvm/ADT/StringMap.h>
+
 #include <stdint.h>
 #include <algorithm>
 #include <optional>
@@ -297,7 +299,7 @@ struct IndexFile {
   std::vector<Range> skipped_by_preprocessor;
 
   std::vector<IndexInclude> includes;
-  std::unordered_map<std::string, int64_t> dependencies;
+  llvm::StringMap<int64_t> dependencies;
   std::unordered_map<Usr, IndexFunc> usr2func;
   std::unordered_map<Usr, IndexType> usr2type;
   std::unordered_map<Usr, IndexVar> usr2var;
diff --git a/src/message_handler.cc b/src/message_handler.cc
index a16f59bb..cf17c013 100644
--- a/src/message_handler.cc
+++ b/src/message_handler.cc
@@ -245,15 +245,14 @@ void EmitSemanticHighlighting(QueryDatabase* db,
             detailed_name.substr(0, detailed_name.find('<'));
         int16_t start_line = sym.range.start.line;
         int16_t start_col = sym.range.start.column;
-        if (start_line >= 0 && start_line < working_file->index_lines.size()) {
-          std::string_view line = working_file->index_lines[start_line];
-          sym.range.end.line = start_line;
-          if (start_col + concise_name.size() <= line.size() &&
-              line.compare(start_col, concise_name.size(), concise_name) == 0)
-            sym.range.end.column = start_col + concise_name.size();
-          else
-            continue;  // applies to for loop
-        }
+        if (start_line < 0 || start_line >= working_file->index_lines.size())
+          continue;
+        std::string_view line = working_file->index_lines[start_line];
+        sym.range.end.line = start_line;
+        if (!(start_col + concise_name.size() <= line.size() &&
+              line.compare(start_col, concise_name.size(), concise_name) == 0))
+          continue;
+        sym.range.end.column = start_col + concise_name.size();
         break;
       }
       case SymbolKind::Type:
diff --git a/src/messages/text_document_definition.cc b/src/messages/text_document_definition.cc
index 103436d1..1d7e545a 100644
--- a/src/messages/text_document_definition.cc
+++ b/src/messages/text_document_definition.cc
@@ -155,7 +155,7 @@ struct Handler_TextDocumentDefinition
             auto pos = name.rfind(query);
             if (pos != std::string::npos) {
               std::get<0>(score) = int(name.size() - query.size());
-              std::get<1>(score) = -pos;
+              std::get<1>(score) = -int(pos);
             }
             if (score < best_score) {
               best_score = score;
diff --git a/src/method.cc b/src/method.cc
index f0ba5ce1..38da766a 100644
--- a/src/method.cc
+++ b/src/method.cc
@@ -12,7 +12,7 @@ MethodType kMethodType_CclsPublishSemanticHighlighting =
 void Reflect(Reader& visitor, lsRequestId& value) {
   if (visitor.IsInt64()) {
     value.type = lsRequestId::kInt;
-    value.value = visitor.GetInt64();
+    value.value = int(visitor.GetInt64());
   } else if (visitor.IsInt()) {
     value.type = lsRequestId::kInt;
     value.value = visitor.GetInt();
diff --git a/src/project.cc b/src/project.cc
index 7f8dfbff..063c9e5a 100644
--- a/src/project.cc
+++ b/src/project.cc
@@ -16,6 +16,8 @@
 #include <llvm/ADT/ArrayRef.h>
 #include <llvm/Option/ArgList.h>
 #include <llvm/Option/OptTable.h>
+#include <llvm/Support/MemoryBuffer.h>
+#include <llvm/Support/LineIterator.h>
 using namespace clang;
 using namespace llvm;
 using namespace llvm::opt;
@@ -29,7 +31,6 @@ using namespace llvm::opt;
 #include <unistd.h>
 #endif
 
-#include <fstream>
 #include <limits>
 #include <unordered_set>
 #include <vector>
@@ -145,14 +146,11 @@ Project::Entry GetCompilationEntryFromCompileCommandEntry(
 
 std::vector<std::string> ReadCompilerArgumentsFromFile(
     const std::string& path) {
+  auto MBOrErr = MemoryBuffer::getFile(path);
+  if (!MBOrErr) return {};
   std::vector<std::string> args;
-  std::ifstream fin(path);
-  for (std::string line; std::getline(fin, line);) {
-    TrimInPlace(line);
-    if (line.empty() || StartsWith(line, "#"))
-      continue;
-    args.push_back(line);
-  }
+  for (line_iterator I(*MBOrErr.get(), true, '#'), E; I != E; ++I)
+    args.push_back(*I);
   return args;
 }
 
diff --git a/src/query.cc b/src/query.cc
index 5ed2d77e..59edfe03 100644
--- a/src/query.cc
+++ b/src/query.cc
@@ -77,7 +77,7 @@ QueryFile::DefUpdate BuildFileDefUpdate(const IndexFile& indexed) {
   def.inactive_regions = std::move(indexed.skipped_by_preprocessor);
   def.dependencies.reserve(indexed.dependencies.size());
   for (auto& dep : indexed.dependencies)
-    def.dependencies.push_back(dep.first);
+    def.dependencies.push_back(dep.first());
   def.language = indexed.language;
 
   auto add_all_symbols = [&](Use use, Usr usr, SymbolKind kind) {
diff --git a/src/query.h b/src/query.h
index f85d986b..0186e070 100644
--- a/src/query.h
+++ b/src/query.h
@@ -3,7 +3,6 @@
 #include "indexer.h"
 #include "serializer.h"
 
-#include <llvm/ADT/DenseMap.h>
 #include <llvm/ADT/SmallVector.h>
 
 struct QueryFile;
@@ -136,10 +135,10 @@ struct QueryDatabase {
   std::vector<SymbolIdx> symbols;
 
   std::vector<QueryFile> files;
-  std::unordered_map<std::string, int> name2file_id;
-  llvm::DenseMap<Usr, QueryFunc> usr2func;
-  llvm::DenseMap<Usr, QueryType> usr2type;
-  llvm::DenseMap<Usr, QueryVar> usr2var;
+  llvm::StringMap<int> name2file_id;
+  std::unordered_map<Usr, QueryFunc> usr2func;
+  std::unordered_map<Usr, QueryType> usr2type;
+  std::unordered_map<Usr, QueryVar> usr2var;
 
   // Marks the given Usrs as invalid.
   void RemoveUsrs(SymbolKind usr_kind, const std::vector<Usr>& to_remove);
diff --git a/src/query_utils.h b/src/query_utils.h
index 3b57ae9d..e76d3212 100644
--- a/src/query_utils.h
+++ b/src/query_utils.h
@@ -11,7 +11,7 @@ Maybe<Use> GetDefinitionExtent(QueryDatabase* db, SymbolIdx sym);
 // Get defining declaration (if exists) or an arbitrary declaration (otherwise)
 // for each id.
 template <typename Q>
-std::vector<Use> GetDeclarations(llvm::DenseMap<Usr, Q>& usr2entity,
+std::vector<Use> GetDeclarations(std::unordered_map<Usr, Q>& usr2entity,
                                  const std::vector<Usr>& usrs) {
   std::vector<Use> ret;
   ret.reserve(usrs.size());
@@ -135,7 +135,7 @@ void EachOccurrenceWithParent(QueryDatabase* db,
 }
 
 template <typename Q, typename Fn>
-void EachDefinedEntity(llvm::DenseMap<Usr, Q>& collection,
+void EachDefinedEntity(std::unordered_map<Usr, Q>& collection,
                        const std::vector<Usr>& usrs,
                        Fn&& fn) {
   for (Usr usr : usrs) {
diff --git a/src/serializer.cc b/src/serializer.cc
index b98abbde..734c147a 100644
--- a/src/serializer.cc
+++ b/src/serializer.cc
@@ -10,6 +10,8 @@
 
 #include <stdexcept>
 
+using namespace llvm;
+
 bool gTestOutputMode = false;
 
 //// Elementary types
@@ -149,6 +151,49 @@ void Reflect(Writer& visitor, JsonNull& value) {
   visitor.Null();
 }
 
+// std::unordered_map
+template <typename V>
+void Reflect(Reader& visitor, std::unordered_map<Usr, V>& map) {
+  visitor.IterArray([&](Reader& entry) {
+    V val;
+    Reflect(entry, val);
+    auto usr = val.usr;
+    map[usr] = std::move(val);
+  });
+}
+template <typename V>
+void Reflect(Writer& visitor, std::unordered_map<Usr, V>& map) {
+  std::vector<std::pair<uint64_t, V>> xs(map.begin(), map.end());
+  std::sort(xs.begin(), xs.end(),
+            [](const auto& a, const auto& b) { return a.first < b.first; });
+  visitor.StartArray(xs.size());
+  for (auto& it : xs)
+    Reflect(visitor, it.second);
+  visitor.EndArray();
+}
+
+// Used by IndexFile::dependencies. Timestamps are emitted for Binary.
+void Reflect(Reader& visitor, StringMap<int64_t>& map) {
+  visitor.IterArray([&](Reader& entry) {
+                      std::string name;
+    Reflect(entry, name);
+    if (visitor.Format() == SerializeFormat::Binary)
+      Reflect(entry, map[name]);
+    else
+      map[name] = 0;
+  });
+}
+void Reflect(Writer& visitor, StringMap<int64_t>& map) {
+  visitor.StartArray(map.size());
+  for (auto& it : map) {
+    std::string key = it.first();
+    Reflect(visitor, key);
+    if (visitor.Format() == SerializeFormat::Binary)
+      Reflect(visitor, it.second);
+  }
+  visitor.EndArray();
+}
+
 // TODO: Move this to indexer.cc
 void Reflect(Reader& visitor, IndexInclude& value) {
   REFLECT_MEMBER_START();
@@ -313,27 +358,6 @@ void Reflect(Writer& visitor, SerializeFormat& value) {
   }
 }
 
-void Reflect(Reader& visitor, std::unordered_map<std::string, int64_t>& map) {
-  visitor.IterArray([&](Reader& entry) {
-                      std::string name;
-    Reflect(entry, name);
-    if (visitor.Format() == SerializeFormat::Binary)
-      Reflect(entry, map[name]);
-    else
-      map[name] = 0;
-  });
-}
-void Reflect(Writer& visitor, std::unordered_map<std::string, int64_t>& map) {
-  visitor.StartArray(map.size());
-  for (auto& it : map) {
-    std::string key = it.first;
-    Reflect(visitor, key);
-    if (visitor.Format() == SerializeFormat::Binary)
-      Reflect(visitor, it.second);
-  }
-  visitor.EndArray();
-}
-
 std::string Serialize(SerializeFormat format, IndexFile& file) {
   switch (format) {
     case SerializeFormat::Binary: {
diff --git a/src/serializer.h b/src/serializer.h
index 3e1bfe87..cc296c79 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -13,7 +13,6 @@
 #include <string>
 #include <string_view>
 #include <type_traits>
-#include <unordered_map>
 #include <vector>
 
 enum class SerializeFormat { Binary, Json };
@@ -282,31 +281,6 @@ void Reflect(Writer& visitor, std::vector<T>& values) {
   visitor.EndArray();
 }
 
-// std::unordered_map
-template <typename V>
-void Reflect(Reader& visitor, std::unordered_map<uint64_t, V>& map) {
-  visitor.IterArray([&](Reader& entry) {
-    V val;
-    Reflect(entry, val);
-    auto usr = val.usr;
-    map[usr] = std::move(val);
-  });
-}
-template <typename V>
-void Reflect(Writer& visitor, std::unordered_map<uint64_t, V>& map) {
-  std::vector<std::pair<uint64_t, V>> xs(map.begin(), map.end());
-  std::sort(xs.begin(), xs.end(),
-            [](const auto& a, const auto& b) { return a.first < b.first; });
-  visitor.StartArray(xs.size());
-  for (auto& it : xs)
-    Reflect(visitor, it.second);
-  visitor.EndArray();
-}
-
-// Used by IndexFile::dependencies. Timestamps are emitted for Binary.
-void Reflect(Reader& visitor, std::unordered_map<std::string, int64_t>& map);
-void Reflect(Writer& visitor, std::unordered_map<std::string, int64_t>& map);
-
 // ReflectMember
 
 template <typename T>