Index: include/__config
===================================================================
--- include/__config
+++ include/__config
@@ -392,15 +392,15 @@
 #elif defined(__ANDROID__)
 #define _LIBCPP_HAS_QUICK_EXIT
 #elif defined(__linux__)
-#if !defined(_LIBCPP_HAS_MUSL_LIBC)
+#if defined(__GLIBC__)
 # include <features.h>
-#if __GLIBC_PREREQ(2, 15)
+#if  __GLIBC_PREREQ(2, 15)
 #define _LIBCPP_HAS_QUICK_EXIT
 #endif
 #if __GLIBC_PREREQ(2, 17)
 #define _LIBCPP_HAS_C11_FEATURES
 #endif
-#else // defined(_LIBCPP_HAS_MUSL_LIBC)
+#else // defined(__GLIBC__)
 #define _LIBCPP_HAS_QUICK_EXIT
 #define _LIBCPP_HAS_C11_FEATURES
 #endif