diff --git a/llvm/include/llvm/Support/TimeProfiler.h b/llvm/include/llvm/Support/TimeProfiler.h
--- a/llvm/include/llvm/Support/TimeProfiler.h
+++ b/llvm/include/llvm/Support/TimeProfiler.h
@@ -14,7 +14,7 @@
 namespace llvm {
 
 struct TimeTraceProfiler;
-extern TimeTraceProfiler *TimeTraceProfilerInstance;
+extern LLVM_THREAD_LOCAL TimeTraceProfiler *TimeTraceProfilerInstance;
 
 /// Initialize the time trace profiler.
 /// This sets up the global \p TimeTraceProfilerInstance
@@ -25,6 +25,9 @@
 /// Cleanup the time trace profiler, if it was initialized.
 void timeTraceProfilerCleanup();
 
+/// Finish a time trace profiler running on a worker thread.
+void timeTraceProfilerFinishThread();
+
 /// Is the time trace profiler enabled, i.e. initialized?
 inline bool timeTraceProfilerEnabled() {
   return TimeTraceProfilerInstance != nullptr;
diff --git a/llvm/lib/Support/TimeProfiler.cpp b/llvm/lib/Support/TimeProfiler.cpp
--- a/llvm/lib/Support/TimeProfiler.cpp
+++ b/llvm/lib/Support/TimeProfiler.cpp
@@ -15,16 +15,25 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/JSON.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Threading.h"
+#include <algorithm>
 #include <cassert>
 #include <chrono>
+#include <mutex>
 #include <string>
 #include <vector>
 
 using namespace std::chrono;
 
+namespace {
+std::mutex Mu;
+std::vector<llvm::TimeTraceProfiler *>
+    ThreadTimeTraceProfilerInstances; // guarded by Mu
+} // namespace
+
 namespace llvm {
 
-TimeTraceProfiler *TimeTraceProfilerInstance = nullptr;
+LLVM_THREAD_LOCAL TimeTraceProfiler *TimeTraceProfilerInstance = nullptr;
 
 typedef duration<steady_clock::rep, steady_clock::period> DurationType;
 typedef time_point<steady_clock> TimePointType;
@@ -61,7 +70,7 @@
 struct TimeTraceProfiler {
   TimeTraceProfiler(unsigned TimeTraceGranularity = 0, StringRef ProcName = "")
       : StartTime(steady_clock::now()), ProcName(ProcName),
-        TimeTraceGranularity(TimeTraceGranularity) {}
+        Tid(llvm::get_threadid()), TimeTraceGranularity(TimeTraceGranularity) {}
 
   void begin(std::string Name, llvm::function_ref<std::string()> Detail) {
     Stack.emplace_back(steady_clock::now(), TimePointType(), std::move(Name),
@@ -103,22 +112,31 @@
     Stack.pop_back();
   }
 
+  // Write events from this TimeTraceProfilerInstance and
+  // ThreadTimeTraceProfilerInstances.
   void Write(raw_pwrite_stream &OS) {
+    // Acquire Mutex as reading ThreadTimeTraceProfilerInstances.
+    std::lock_guard<std::mutex> Lock(Mu);
     assert(Stack.empty() &&
            "All profiler sections should be ended when calling Write");
+    assert(std::all_of(ThreadTimeTraceProfilerInstances.begin(),
+                       ThreadTimeTraceProfilerInstances.end(),
+                       [](const auto &TTP) { return TTP->Stack.empty(); }) &&
+           "All profiler sections should be ended when calling Write");
+
     json::OStream J(OS);
     J.objectBegin();
     J.attributeBegin("traceEvents");
     J.arrayBegin();
 
     // Emit all events for the main flame graph.
-    for (const auto &E : Entries) {
+    auto writeEvent = [&](const auto &E, uint64_t Tid) {
       auto StartUs = E.getFlameGraphStartUs(StartTime);
       auto DurUs = E.getFlameGraphDurUs();
 
       J.object([&]{
         J.attribute("pid", 1);
-        J.attribute("tid", 0);
+        J.attribute("tid", int64_t(Tid));
         J.attribute("ph", "X");
         J.attribute("ts", StartUs);
         J.attribute("dur", DurUs);
@@ -127,39 +145,73 @@
           J.attributeObject("args", [&] { J.attribute("detail", E.Detail); });
         }
       });
+    };
+    for (const auto &E : Entries) {
+      writeEvent(E, this->Tid);
+    }
+    for (const auto &TTP : ThreadTimeTraceProfilerInstances) {
+      for (const auto &E : TTP->Entries) {
+        writeEvent(E, TTP->Tid);
+      }
     }
 
     // Emit totals by section name as additional "thread" events, sorted from
     // longest one.
-    int Tid = 1;
+    // Find highest used thread id.
+    uint64_t MaxTid = this->Tid;
+    for (const auto &TTP : ThreadTimeTraceProfilerInstances) {
+      MaxTid = std::max(MaxTid, TTP->Tid);
+    }
+
+    // Combine all CountAndTotalPerName from threads into one.
+    StringMap<CountAndDurationType> AllCountAndTotalPerName;
+    auto combineStat = [&](const auto &Stat) {
+      std::string Key = Stat.getKey();
+      auto Value = Stat.getValue();
+      auto &CountAndTotal = AllCountAndTotalPerName[Key];
+      CountAndTotal.first += Value.first;
+      CountAndTotal.second += Value.second;
+    };
+    for (const auto &Stat : CountAndTotalPerName) {
+      combineStat(Stat);
+    }
+    for (const auto &TTP : ThreadTimeTraceProfilerInstances) {
+      for (const auto &Stat : TTP->CountAndTotalPerName) {
+        combineStat(Stat);
+      }
+    }
+
     std::vector<NameAndCountAndDurationType> SortedTotals;
-    SortedTotals.reserve(CountAndTotalPerName.size());
-    for (const auto &E : CountAndTotalPerName)
-      SortedTotals.emplace_back(E.getKey(), E.getValue());
+    SortedTotals.reserve(AllCountAndTotalPerName.size());
+    for (const auto &Total : AllCountAndTotalPerName)
+      SortedTotals.emplace_back(Total.getKey(), Total.getValue());
 
     llvm::sort(SortedTotals.begin(), SortedTotals.end(),
                [](const NameAndCountAndDurationType &A,
                   const NameAndCountAndDurationType &B) {
                  return A.second.second > B.second.second;
                });
-    for (const auto &E : SortedTotals) {
-      auto DurUs = duration_cast<microseconds>(E.second.second).count();
-      auto Count = CountAndTotalPerName[E.first].first;
+
+    // Report totals on separate threads of tracing file.
+    uint64_t TotalTid = MaxTid + 1;
+    for (const auto &Total : SortedTotals) {
+      auto DurUs = duration_cast<microseconds>(Total.second.second).count();
+      auto Count = AllCountAndTotalPerName[Total.first].first;
 
       J.object([&]{
         J.attribute("pid", 1);
-        J.attribute("tid", Tid);
+        J.attribute("tid", int64_t(TotalTid));
         J.attribute("ph", "X");
         J.attribute("ts", 0);
         J.attribute("dur", DurUs);
-        J.attribute("name", "Total " + E.first);
+        J.attribute("name", "Total " + Total.first);
         J.attributeObject("args", [&] {
           J.attribute("count", int64_t(Count));
           J.attribute("avg ms", int64_t(DurUs / Count / 1000));
         });
       });
 
-      ++Tid;
+      ++TotalTid;
     }
 
     // Emit metadata event with process name.
@@ -183,6 +235,7 @@
   StringMap<CountAndDurationType> CountAndTotalPerName;
   const TimePointType StartTime;
   const std::string ProcName;
+  const uint64_t Tid;
 
   // Minimum time granularity (in microseconds)
   const unsigned TimeTraceGranularity;
@@ -196,8 +249,21 @@
       TimeTraceGranularity, llvm::sys::path::filename(ProcName));
 }
 
+// Removes all TimeTraceProfilerInstances.
+// Called from main thread.
 void timeTraceProfilerCleanup() {
   delete TimeTraceProfilerInstance;
+  std::lock_guard<std::mutex> Lock(Mu);
+  for (auto TTP : ThreadTimeTraceProfilerInstances)
+    delete TTP;
+  ThreadTimeTraceProfilerInstances.clear();
+}
+
+// Finish TimeTraceProfilerInstance on a worker thread.
+// This doesn't remove the instance, just moves the pointer to global vector.
+void timeTraceProfilerFinishThread() {
+  std::lock_guard<std::mutex> Lock(Mu);
+  ThreadTimeTraceProfilerInstances.push_back(TimeTraceProfilerInstance);
   TimeTraceProfilerInstance = nullptr;
 }