Index: clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp
===================================================================
--- clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp
+++ clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp
@@ -66,6 +66,27 @@
   return Requests;
 }
 
+// This is not a *real* benchmark: it shows size of built MemIndex (in bytes).
+// Same for the next "benchmark".
+// FIXME(kbobyrev): Should this be separated into the BackingMemorySize
+// (underlying SymbolSlab size) and Symbol Index (MemIndex/Dex) overhead?
+static void MemSize(benchmark::State &State) {
+  const auto Mem = buildMem();
+  for (auto _ : State)
+    // Divide size of Mem by 1000 so that it will be correctly displayed in the
+    // benchmark report (possible options for time units are ms, ns and us).
+    State.SetIterationTime(/*double Seconds=*/Mem->estimateMemoryUsage() /
+                           1000);
+}
+BENCHMARK(MemSize)->UseManualTime()->Unit(benchmark::kMillisecond);
+
+static void DexSize(benchmark::State &State) {
+  const auto Dex = buildDex();
+  for (auto _ : State)
+    State.SetIterationTime(Dex->estimateMemoryUsage() / 1000);
+}
+BENCHMARK(DexSize)->UseManualTime()->Unit(benchmark::kMillisecond);
+
 static void MemQueries(benchmark::State &State) {
   const auto Mem = buildMem();
   const auto Requests = extractQueriesFromLogs();
@@ -73,7 +94,7 @@
     for (const auto &Request : Requests)
       Mem->fuzzyFind(Request, [](const Symbol &S) {});
 }
-BENCHMARK(MemQueries);
+BENCHMARK(MemQueries)->Unit(benchmark::kMillisecond);
 
 static void DexQueries(benchmark::State &State) {
   const auto Dex = buildDex();
@@ -82,7 +103,7 @@
     for (const auto &Request : Requests)
       Dex->fuzzyFind(Request, [](const Symbol &S) {});
 }
-BENCHMARK(DexQueries);
+BENCHMARK(DexQueries)->Unit(benchmark::kMillisecond);
 
 } // namespace
 } // namespace clangd
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 "Logger.h"
 #include "Serialization.h"
 #include "Trace.h"
 #include "dex/Dex.h"
@@ -225,8 +226,12 @@
   if (!Slab)
     return nullptr;
   trace::Span Tracer("BuildIndex");
-  return UseDex ? dex::Dex::build(std::move(*Slab), URISchemes)
-                : MemIndex::build(std::move(*Slab), RefSlab());
+  auto Index = UseDex ? dex::Dex::build(std::move(*Slab), URISchemes)
+                      : MemIndex::build(std::move(*Slab), RefSlab());
+  vlog("Loaded {0} from {1} with estimated memory usage {2}",
+       UseDex ? "Dex" : "MemIndex", SymbolFilename,
+       Index->estimateMemoryUsage());
+  return Index;
 }
 
 } // namespace clangd
Index: clang-tools-extra/clangd/index/dex/Dex.cpp
===================================================================
--- clang-tools-extra/clangd/index/dex/Dex.cpp
+++ clang-tools-extra/clangd/index/dex/Dex.cpp
@@ -124,9 +124,6 @@
   for (const auto &TokenToPostingList : TempInvertedIndex)
     InvertedIndex.insert({TokenToPostingList.first,
                           PostingList(move(TokenToPostingList.second))});
-
-  vlog("Built Dex with estimated memory usage {0} bytes.",
-       estimateMemoryUsage());
 }
 
 /// Constructs iterators over tokens extracted from the query and exhausts it
@@ -239,7 +236,7 @@
   Bytes += LookupTable.getMemorySize();
   Bytes += InvertedIndex.getMemorySize();
   for (const auto &P : InvertedIndex)
-    Bytes += P.second.bytes();
+    Bytes += P.first.Data.size() + P.second.bytes() * sizeof(DocID);
   return Bytes + BackingDataSize;
 }