diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_stackdepot.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_stackdepot.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_stackdepot.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_stackdepot.cpp
@@ -12,6 +12,7 @@
 
 #include "sanitizer_stackdepot.h"
 
+#include "sanitizer_atomic.h"
 #include "sanitizer_common.h"
 #include "sanitizer_hash.h"
 #include "sanitizer_stack_store.h"
@@ -81,10 +82,15 @@
   return pack;
 }
 
+static Semaphore compress_semaphore;
+
+// 0 - didn't try, 1 - started or pending, 2 - failed.
+static atomic_uint8_t thread_started;
+
 static void CompressTraces() {
   u64 start = MonotonicNanoTime();
   uptr diff = stackStore.Pack(static_cast<StackStore::Compression>(
-      common_flags()->compress_stack_depot));
+      Abs(common_flags()->compress_stack_depot)));
   if (!diff)
     return;
   u64 finish = MonotonicNanoTime();
@@ -93,8 +99,37 @@
           (finish - start) / 1000000);
 }
 
+static void *CompressTracesThread(void *args) {
+  for (;;) {
+    compress_semaphore.Wait();
+    CompressTraces();
+  }
+  return nullptr;
+}
+
+static bool MaybeRunBackgroundThread() {
+  if (common_flags()->compress_stack_depot < 0 /* hack for testing */)
+    return false;
+
+  u8 cmp = 0;
+  if (!atomic_compare_exchange_weak(&thread_started, &cmp, 1,
+                                    memory_order_acquire)) {
+    return cmp == 1;
+  }
+  if (!internal_start_thread(&CompressTracesThread, nullptr)) {
+    atomic_store(&thread_started, 2, memory_order_release);
+    return false;
+  }
+  VPrintf(1, "%s: StackDepot Thread Started\n", SanitizerToolName);
+  return true;
+}
+
 void StackDepotNode::post_process() {
-  if (common_flags()->compress_stack_depot)
+  if (!common_flags()->compress_stack_depot)
+    return;
+  if (MaybeRunBackgroundThread())
+    compress_semaphore.Post(1);
+  else
     CompressTraces();
 }
 
diff --git a/compiler-rt/test/sanitizer_common/TestCases/compress_stack_depot.cpp b/compiler-rt/test/sanitizer_common/TestCases/compress_stack_depot.cpp
--- a/compiler-rt/test/sanitizer_common/TestCases/compress_stack_depot.cpp
+++ b/compiler-rt/test/sanitizer_common/TestCases/compress_stack_depot.cpp
@@ -1,6 +1,6 @@
 // RUN: %clangxx %s -fsanitize-memory-track-origins=1 -o %t
 // RUN: %env_tool_opts="compress_stack_depot=0:malloc_context_size=128:verbosity=1" %run %t 2>&1 | FileCheck %s --implicit-check-not="StackDepot released"
-// RUN: %env_tool_opts="compress_stack_depot=1:malloc_context_size=128:verbosity=1" %run %t 2>&1 | FileCheck %s --check-prefixes=COMPRESS
+// RUN: %env_tool_opts="compress_stack_depot=-1:malloc_context_size=128:verbosity=1" %run %t 2>&1 | FileCheck %s --check-prefixes=COMPRESS
 
 // Ubsan does not store stacks.
 // UNSUPPORTED: ubsan