diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -1133,13 +1133,7 @@
   sortSegmentsAndSections();
   createLoadCommands<LP>();
   finalizeAddresses();
-  threadPool.async([&] {
-    if (LLVM_ENABLE_THREADS && config->timeTraceEnabled)
-      timeTraceProfilerInitialize(config->timeTraceGranularity, "writeMapFile");
-    writeMapFile();
-    if (LLVM_ENABLE_THREADS && config->timeTraceEnabled)
-      timeTraceProfilerFinishThread();
-  });
+  threadPool.async(writeMapFile);
   finalizeLinkEditSegment();
   writeOutputFile();
 }
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
@@ -25,6 +25,10 @@
 void timeTraceProfilerInitialize(unsigned TimeTraceGranularity,
                                  StringRef ProcName);
 
+/// Initialize the time trace profiler with the same settings as Profiler.
+void timeTraceProfilerInitialize(const TimeTraceProfiler &Profiler,
+                                 StringRef ProcName);
+
 /// Cleanup the time trace profiler, if it was initialized.
 void timeTraceProfilerCleanup();
 
diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -1268,9 +1268,6 @@
                 &ResolvedODR,
             const GVSummaryMapTy &DefinedGlobals,
             MapVector<StringRef, BitcodeModule> &ModuleMap) {
-          if (LLVM_ENABLE_THREADS && Conf.TimeTraceEnabled)
-            timeTraceProfilerInitialize(Conf.TimeTraceGranularity,
-                                        "thin backend");
           Error E = runThinLTOBackendThread(
               AddStream, Cache, Task, BM, CombinedIndex, ImportList, ExportList,
               ResolvedODR, DefinedGlobals, ModuleMap);
@@ -1281,8 +1278,6 @@
             else
               Err = std::move(E);
           }
-          if (LLVM_ENABLE_THREADS && Conf.TimeTraceEnabled)
-            timeTraceProfilerFinishThread();
         },
         BM, std::ref(CombinedIndex), std::ref(ImportList), std::ref(ExportList),
         std::ref(ResolvedODR), std::ref(DefinedGlobals), std::ref(ModuleMap));
diff --git a/llvm/lib/Support/ThreadPool.cpp b/llvm/lib/Support/ThreadPool.cpp
--- a/llvm/lib/Support/ThreadPool.cpp
+++ b/llvm/lib/Support/ThreadPool.cpp
@@ -15,7 +15,9 @@
 #include "llvm/Config/llvm-config.h"
 
 #if LLVM_ENABLE_THREADS
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/Support/Threading.h"
+#include "llvm/Support/TimeProfiler.h"
 #else
 #include "llvm/Support/raw_ostream.h"
 #endif
@@ -32,9 +34,16 @@
   if (Threads.size() >= MaxThreadCount)
     return; // Already hit the max thread pool size.
   int newThreadCount = std::min<int>(requested, MaxThreadCount);
+  TimeTraceProfiler *MainThreadProfiler = getTimeTraceProfilerInstance();
   while (static_cast<int>(Threads.size()) < newThreadCount) {
     int ThreadID = Threads.size();
-    Threads.emplace_back([this, ThreadID] {
+    Threads.emplace_back([this, MainThreadProfiler, ThreadID] {
+      if (MainThreadProfiler)
+        timeTraceProfilerInitialize(*MainThreadProfiler, "worker");
+      auto ProfilerFinish = make_scope_exit([] {
+        if (timeTraceProfilerEnabled())
+          timeTraceProfilerFinishThread();
+      });
       Strategy.apply_thread_strategy(ThreadID);
       while (true) {
         std::function<void()> Task;
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
@@ -267,6 +267,11 @@
       TimeTraceGranularity, llvm::sys::path::filename(ProcName));
 }
 
+void llvm::timeTraceProfilerInitialize(const TimeTraceProfiler &Profiler,
+                                       StringRef ProcName) {
+  timeTraceProfilerInitialize(Profiler.TimeTraceGranularity, ProcName);
+}
+
 // Removes all TimeTraceProfilerInstances.
 // Called from main thread.
 void llvm::timeTraceProfilerCleanup() {