diff --git a/llvm/lib/Support/Unix/Threading.inc b/llvm/lib/Support/Unix/Threading.inc
--- a/llvm/lib/Support/Unix/Threading.inc
+++ b/llvm/lib/Support/Unix/Threading.inc
@@ -26,12 +26,9 @@
 #include <pthread_np.h> // For pthread_getthreadid_np() / pthread_set_name_np()
 #endif
 
-#if defined(__FreeBSD__)
-#include <sys/cpuset.h>
-#endif
-
 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
 #include <errno.h>
+#include <sys/cpuset.h>
 #include <sys/sysctl.h>
 #include <sys/user.h>
 #include <unistd.h>
@@ -286,14 +283,13 @@
 #include <thread>
 
 int computeHostNumHardwareThreads() {
-#ifdef __FreeBSD__
+#if defined(__FreeBSD__)
   cpuset_t mask;
   CPU_ZERO(&mask);
   if (cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, sizeof(mask),
                          &mask) == 0)
     return CPU_COUNT(&mask);
-#endif
-#ifdef __linux__
+#elif defined(__linux__)
   cpu_set_t Set;
   if (sched_getaffinity(0, sizeof(Set), &Set) == 0)
     return CPU_COUNT(&Set);