diff --git a/contrib/libllvmlibc-cmake/CMakeLists.txt b/contrib/libllvmlibc-cmake/CMakeLists.txt
index 3eaeaf30a79a..e11d93d9aa85 100644
--- a/contrib/libllvmlibc-cmake/CMakeLists.txt
+++ b/contrib/libllvmlibc-cmake/CMakeLists.txt
@@ -62,6 +62,7 @@ set(LLVMLIBC_DEFS_COMMON
     LIBC_MATH_HAS_NO_ERRNO=1
     LIBC_MATH_HAS_NO_EXCEPT=1
     LIBC_MATH_HAS_SKIP_ACCURATE_PASS=1
+    LIBC_ERRNO_MODE=6
 )
 
 if (ARCH_AMD64)