diff --git a/lldb/unittests/Host/MainLoopTest.cpp b/lldb/unittests/Host/MainLoopTest.cpp
--- a/lldb/unittests/Host/MainLoopTest.cpp
+++ b/lldb/unittests/Host/MainLoopTest.cpp
@@ -32,17 +32,13 @@
     ASSERT_TRUE(error.Success());
 
     Socket *accept_socket;
-    std::future<Status> accept_error = std::async(std::launch::async, [&] {
-      return listen_socket_up->Accept(accept_socket);
-    });
-
     std::unique_ptr<TCPSocket> connect_socket_up(
         new TCPSocket(true, child_processes_inherit));
     error = connect_socket_up->Connect(
         llvm::formatv("localhost:{0}", listen_socket_up->GetLocalPortNumber())
             .str());
     ASSERT_TRUE(error.Success());
-    ASSERT_TRUE(accept_error.get().Success());
+    ASSERT_TRUE(listen_socket_up->Accept(accept_socket).Success());
 
     callback_count = 0;
     socketpair[0] = std::move(connect_socket_up);
@@ -174,7 +170,7 @@
 
   auto handle = loop.RegisterSignal(SIGUSR1, make_callback(), error);
   ASSERT_TRUE(error.Success());
-  kill(getpid(), SIGUSR1);
+  pthread_kill(pthread_self(), SIGUSR1);
   ASSERT_TRUE(loop.Run().Success());
   ASSERT_EQ(1u, callback_count);
 }
@@ -192,14 +188,9 @@
 
   auto handle = loop.RegisterSignal(SIGUSR1, make_callback(), error);
   ASSERT_TRUE(error.Success());
-  std::thread killer([]() {
-    sleep(1);
-    kill(getpid(), SIGUSR2);
-    sleep(1);
-    kill(getpid(), SIGUSR1);
-  });
+  pthread_kill(pthread_self(), SIGUSR2);
+  pthread_kill(pthread_self(), SIGUSR1);
   ASSERT_TRUE(loop.Run().Success());
-  killer.join();
   ASSERT_EQ(1u, callback_count);
 }
 
@@ -220,7 +211,7 @@
         SIGUSR1, [&](MainLoopBase &loop) { ++callback2_count; }, error);
     ASSERT_TRUE(error.Success());
 
-    kill(getpid(), SIGUSR1);
+    pthread_kill(pthread_self(), SIGUSR1);
     ASSERT_TRUE(loop.Run().Success());
     ASSERT_EQ(1u, callback_count);
     ASSERT_EQ(1u, callback2_count);
@@ -233,7 +224,7 @@
         SIGUSR1, [&](MainLoopBase &loop) { ++callback3_count; }, error);
     ASSERT_TRUE(error.Success());
 
-    kill(getpid(), SIGUSR1);
+    pthread_kill(pthread_self(), SIGUSR1);
     ASSERT_TRUE(loop.Run().Success());
     ASSERT_EQ(2u, callback_count);
     ASSERT_EQ(1u, callback2_count);
@@ -241,7 +232,7 @@
   }
 
   // Both extra callbacks should be unregistered now.
-  kill(getpid(), SIGUSR1);
+  pthread_kill(pthread_self(), SIGUSR1);
   ASSERT_TRUE(loop.Run().Success());
   ASSERT_EQ(3u, callback_count);
   ASSERT_EQ(1u, callback2_count);