diff --git a/tests/incremental/foreign.rs b/tests/incremental/foreign.rs
index cb040fe1296..1af203e9b77 100644
--- a/tests/incremental/foreign.rs
+++ b/tests/incremental/foreign.rs
@@ -1,38 +1,21 @@
 // Test what happens we save incremental compilation state that makes
 // use of foreign items. This used to ICE (#34991).
-//@ ignore-sgx no libc
-
 //@ revisions: rpass1
 
-#![feature(rustc_private)]
-
-extern crate libc;
-
 use std::ffi::CString;
 
 mod mlibc {
-    use libc::{c_char, c_long, c_longlong};
-
     extern "C" {
-        pub fn atol(x: *const c_char) -> c_long;
-        pub fn atoll(x: *const c_char) -> c_longlong;
+        // strlen is provided either by an external library or compiler-builtins as a fallback
+        pub fn strlen(x: *const std::ffi::c_char) -> usize;
     }
 }
 
-fn atol(s: String) -> isize {
+fn strlen(s: String) -> usize {
     let c = CString::new(s).unwrap();
-    unsafe { mlibc::atol(c.as_ptr()) as isize }
-}
-
-fn atoll(s: String) -> i64 {
-    let c = CString::new(s).unwrap();
-    unsafe { mlibc::atoll(c.as_ptr()) as i64 }
+    unsafe { mlibc::strlen(c.as_ptr()) }
 }
 
 pub fn main() {
-    assert_eq!(atol("1024".to_string()) * 10, atol("10240".to_string()));
-    assert_eq!(
-        (atoll("11111111111111111".to_string()) * 10),
-        atoll("111111111111111110".to_string())
-    );
+    assert_eq!(strlen("1024".to_string()), strlen("2048".to_string()));
 }