Index: clang-tools-extra/clangd/CMakeLists.txt
===================================================================
--- clang-tools-extra/clangd/CMakeLists.txt
+++ clang-tools-extra/clangd/CMakeLists.txt
@@ -71,3 +71,7 @@
 endif()
 add_subdirectory(tool)
 add_subdirectory(global-symbol-builder)
+
+if (LLVM_BUILD_BENCHMARKS)
+  add_subdirectory(benchmarks)
+endif()
Index: clang-tools-extra/clangd/benchmarks/CMakeLists.txt
===================================================================
--- /dev/null
+++ clang-tools-extra/clangd/benchmarks/CMakeLists.txt
@@ -0,0 +1,2 @@
+add_executable(IndexBenchmark IndexBenchmark.cpp)
+target_link_libraries(IndexBenchmark benchmark clangDaemon LLVMSupport)
Index: clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp
@@ -0,0 +1,93 @@
+//===--- DexBenchmark.cpp - DexIndex benchmarks -----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../index/SymbolYAML.h"
+#include "../index/dex/DexIndex.h"
+#include "benchmark/benchmark.h"
+
+// FIXME(kbobyrev): Get rid of global variables and put them into
+// benchmark::State?
+std::unique_ptr<clang::clangd::SymbolIndex> Dex;
+std::unique_ptr<clang::clangd::SymbolIndex> Mem;
+
+std::vector<clang::clangd::FuzzyFindRequest> Requests;
+
+std::string IndexFilename;
+
+void initializeEnvironment(char *argv[]) {
+  IndexFilename = argv[1];
+
+  Dex = clang::clangd::buildStaticIndex(IndexFilename, true);
+  Mem = clang::clangd::buildStaticIndex(IndexFilename, false);
+
+  // FXIME(kbobyrev): Add more requests.
+  clang::clangd::FuzzyFindRequest R;
+  R.MaxCandidateCount = 100;
+  Requests.push_back(R);
+  R.Scopes = {"::"};
+  Requests.push_back(R);
+  R.Scopes = {"::", "llvm::", "clang::", "clangd::"};
+  Requests.push_back(R);
+  R.Scopes = {"::", "clang::", "llvm::", "std::"};
+  R.Query = "TUDec";
+  Requests.push_back(R);
+  R.Query = "non-existent symbol";
+  Requests.push_back(R);
+}
+
+namespace clang {
+namespace clangd {
+namespace dex {
+
+static void BuildMem(benchmark::State &State) {
+  for (auto _ : State)
+    Mem = clang::clangd::buildStaticIndex(IndexFilename, false);
+}
+BENCHMARK(BuildMem);
+
+static void MemAdHocQueries(benchmark::State &State) {
+  for (auto _ : State)
+    for (const auto Req : Requests)
+      Mem->fuzzyFind(Req, [](const Symbol &S) {});
+}
+BENCHMARK(MemAdHocQueries);
+
+static void BuildDex(benchmark::State &State) {
+  for (auto _ : State)
+    Dex = clang::clangd::buildStaticIndex(IndexFilename, true);
+}
+BENCHMARK(BuildDex);
+
+static void DexAdHocQueries(benchmark::State &State) {
+  for (auto _ : State)
+    for (const auto Req : Requests)
+      Dex->fuzzyFind(Req, [](const Symbol &S) {});
+}
+BENCHMARK(DexAdHocQueries);
+
+} // namespace dex
+} // namespace clangd
+} // namespace clang
+
+// FIXME(kbobyrev): Extract fuzzyFind requests from the user logs (-log=verbose)
+// and add a separate benchmark target for a bunch of user-provided fuzzy find
+// requests.
+int main(int argc, char *argv[]) {
+  if (argc < 2) {
+    llvm::errs() << "Usage: " << argv[0]
+                 << " global-symbol-index.yaml BENCHMARK_OPTIONS...\n";
+    return -1;
+  }
+  initializeEnvironment(argv);
+  // Trim first two arguments of the benchmark invocation.
+  argv += 2;
+  argc -= 2;
+  ::benchmark::Initialize(&argc, argv);
+  ::benchmark::RunSpecifiedBenchmarks();
+}
Index: clang-tools-extra/clangd/index/SymbolYAML.h
===================================================================
--- clang-tools-extra/clangd/index/SymbolYAML.h
+++ clang-tools-extra/clangd/index/SymbolYAML.h
@@ -42,6 +42,12 @@
 // The YAML result is safe to concatenate if you have multiple symbol slabs.
 void SymbolsToYAML(const SymbolSlab &Symbols, llvm::raw_ostream &OS);
 
+// Build an in-memory static index for global symbols from a YAML-format file.
+// The size of global symbols should be relatively small, so that all symbols
+// can be managed in memory.
+std::unique_ptr<SymbolIndex> buildStaticIndex(llvm::StringRef YamlSymbolFile,
+                                              bool UseDex);
+
 } // namespace clangd
 } // namespace clang
 
Index: clang-tools-extra/clangd/index/SymbolYAML.cpp
===================================================================
--- clang-tools-extra/clangd/index/SymbolYAML.cpp
+++ clang-tools-extra/clangd/index/SymbolYAML.cpp
@@ -9,6 +9,7 @@
 
 #include "SymbolYAML.h"
 #include "Index.h"
+#include "dex/DexIndex.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -203,5 +204,21 @@
   return OS.str();
 }
 
+std::unique_ptr<SymbolIndex> buildStaticIndex(llvm::StringRef YamlSymbolFile,
+                                              bool UseDex) {
+  auto Buffer = llvm::MemoryBuffer::getFile(YamlSymbolFile);
+  if (!Buffer) {
+    llvm::errs() << "Can't open " << YamlSymbolFile << "\n";
+    return nullptr;
+  }
+  auto Slab = symbolsFromYAML(Buffer.get()->getBuffer());
+  SymbolSlab::Builder SymsBuilder;
+  for (auto Sym : Slab)
+    SymsBuilder.insert(Sym);
+
+  return UseDex ? dex::DexIndex::build(std::move(SymsBuilder).build())
+                : MemIndex::build(std::move(SymsBuilder).build());
+}
+
 } // namespace clangd
 } // namespace clang
Index: clang-tools-extra/clangd/index/dex/DexIndex.cpp
===================================================================
--- clang-tools-extra/clangd/index/dex/DexIndex.cpp
+++ clang-tools-extra/clangd/index/dex/DexIndex.cpp
@@ -161,7 +161,6 @@
   }
 }
 
-
 void DexIndex::findOccurrences(
     const OccurrencesRequest &Req,
     llvm::function_ref<void(const SymbolOccurrence &)> Callback) const {
Index: clang-tools-extra/clangd/tool/ClangdMain.cpp
===================================================================
--- clang-tools-extra/clangd/tool/ClangdMain.cpp
+++ clang-tools-extra/clangd/tool/ClangdMain.cpp
@@ -38,24 +38,6 @@
 
 enum class PCHStorageFlag { Disk, Memory };
 
-// Build an in-memory static index for global symbols from a YAML-format file.
-// The size of global symbols should be relatively small, so that all symbols
-// can be managed in memory.
-std::unique_ptr<SymbolIndex> buildStaticIndex(llvm::StringRef YamlSymbolFile) {
-  auto Buffer = llvm::MemoryBuffer::getFile(YamlSymbolFile);
-  if (!Buffer) {
-    llvm::errs() << "Can't open " << YamlSymbolFile << "\n";
-    return nullptr;
-  }
-  auto Slab = symbolsFromYAML(Buffer.get()->getBuffer());
-  SymbolSlab::Builder SymsBuilder;
-  for (auto Sym : Slab)
-    SymsBuilder.insert(Sym);
-
-  return UseDex ? dex::DexIndex::build(std::move(SymsBuilder).build())
-                : MemIndex::build(std::move(SymsBuilder).build());
-}
-
 } // namespace
 
 static llvm::cl::opt<Path> CompileCommandsDir(
@@ -294,7 +276,7 @@
   Opts.BuildDynamicSymbolIndex = EnableIndex;
   std::unique_ptr<SymbolIndex> StaticIdx;
   if (EnableIndex && !YamlSymbolFile.empty()) {
-    StaticIdx = buildStaticIndex(YamlSymbolFile);
+    StaticIdx = buildStaticIndex(YamlSymbolFile, UseDex);
     Opts.StaticIndex = StaticIdx.get();
   }
   Opts.AsyncThreadsCount = WorkerThreadsCount;