diff --git a/compiler-rt/test/lsan/TestCases/many_threads.cpp b/compiler-rt/test/lsan/TestCases/many_threads.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/lsan/TestCases/many_threads.cpp
@@ -0,0 +1,94 @@
+// Test that threads are reused.
+// RUN: %clangxx_lsan %s -o %t -lpthread
+// RUN: %run %t 2>&1
+
+#include <pthread.h>
+#include <stdlib.h>
+
+pthread_mutex_t mu = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
+
+static const size_t kTestThreads = 10000;
+
+void *waiting_func(void *args) {
+  pthread_mutex_lock(&mu);
+  pthread_cond_broadcast(&cond);
+  pthread_mutex_unlock(&mu);
+  return NULL;
+}
+
+void *null_func(void *args) {
+  return NULL;
+}
+
+void join(void) {
+  for (size_t i = 0; i < kTestThreads; i++) {
+    pthread_t thread;
+    pthread_create(&thread, NULL, null_func, NULL);
+    pthread_join(thread, NULL);
+  }
+}
+
+void join_exited(void) {
+  pthread_mutex_lock(&mu);
+
+  for (size_t i = 0; i < kTestThreads; i++) {
+    pthread_t thread;
+    pthread_create(&thread, NULL, waiting_func, NULL);
+    pthread_cond_wait(&cond, &mu);
+    pthread_join(thread, NULL);
+  }
+
+  pthread_mutex_unlock(&mu);
+}
+
+void detach_live(void) {
+  pthread_mutex_lock(&mu);
+
+  for (size_t i = 0; i < kTestThreads; i++) {
+    pthread_t thread;
+    pthread_create(&thread, NULL, waiting_func, NULL);
+    pthread_cond_wait(&cond, &mu);
+    pthread_detach(thread);
+  }
+
+  pthread_mutex_unlock(&mu);
+}
+
+void detach_exited(void) {
+  pthread_mutex_lock(&mu);
+
+  for (size_t i = 0; i < kTestThreads; i++) {
+    pthread_t thread;
+    pthread_create(&thread, NULL, waiting_func, NULL);
+    pthread_detach(thread);
+    pthread_cond_wait(&cond, &mu);
+  }
+
+  pthread_mutex_unlock(&mu);
+}
+
+void starts_detached(void) {
+  pthread_attr_t attrs;
+  pthread_attr_init(&attrs);
+  pthread_attr_setdetachstate(&attrs, PTHREAD_CREATE_DETACHED);
+
+  pthread_mutex_lock(&mu);
+
+  for (size_t i = 0; i < kTestThreads; i++) {
+    pthread_t thread;
+    pthread_create(&thread, &attrs, waiting_func, NULL);
+    pthread_cond_wait(&cond, &mu);
+  }
+
+  pthread_mutex_unlock(&mu);
+}
+
+int main() {
+  detach_live();
+  detach_exited();
+  starts_detached();
+  join();
+  join_exited();
+  return 0;
+}