diff --git a/libcxx/src/thread.cpp b/libcxx/src/thread.cpp
--- a/libcxx/src/thread.cpp
+++ b/libcxx/src/thread.cpp
@@ -23,7 +23,7 @@
 # include <sys/param.h>
 #endif
 
-#if __has_include(<sys/sysctl.h>)
+#if !defined(_LIBCPP_HAS_MUSL_LIBC) && __has_include(<sys/sysctl.h>)
 # include <sys/sysctl.h>
 #endif