diff --git a/libcxx/include/__threading_support b/libcxx/include/__threading_support
--- a/libcxx/include/__threading_support
+++ b/libcxx/include/__threading_support
@@ -14,7 +14,8 @@
 #include <__chrono/convert_to_timespec.h>
 #include <__chrono/duration.h>
 #include <__config>
-#include <__thread/poll_with_backoff.h>
+#include <__fwd/hash.h>
+#include <ctime>
 #include <errno.h>
 
 #ifdef __MVS__
diff --git a/libcxx/include/semaphore b/libcxx/include/semaphore
--- a/libcxx/include/semaphore
+++ b/libcxx/include/semaphore
@@ -52,6 +52,7 @@
 #include <__availability>
 #include <__chrono/time_point.h>
 #include <__config>
+#include <__thread/poll_with_backoff.h>
 #include <__thread/timed_backoff_policy.h>
 #include <__threading_support>
 #include <cstddef>
diff --git a/libcxx/src/support/win32/thread_win32.cpp b/libcxx/src/support/win32/thread_win32.cpp
--- a/libcxx/src/support/win32/thread_win32.cpp
+++ b/libcxx/src/support/win32/thread_win32.cpp
@@ -7,6 +7,8 @@
 //===----------------------------------------------------------------------===//
 
 #include <__threading_support>
+#include <chrono>
+
 #define NOMINMAX
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>