diff --git a/src/compiletest/compiletest.rs b/src/compiletest/compiletest.rs
index be8f9655010..969f4e4373a 100644
--- a/src/compiletest/compiletest.rs
+++ b/src/compiletest/compiletest.rs
@@ -16,6 +16,7 @@
 extern mod extra;
 
 use std::os;
+use std::rt;
 use std::f64;
 
 use extra::getopts;
@@ -223,6 +224,10 @@ pub fn mode_str(mode: mode) -> ~str {
 pub fn run_tests(config: &config) {
     let opts = test_opts(config);
     let tests = make_tests(config);
+    // sadly osx needs some file descriptor limits raised for running tests in
+    // parallel (especially when we have lots and lots of child processes).
+    // For context, see #8904
+    rt::test::prepare_for_lots_of_tests();
     let res = test::run_tests_console(&opts, tests);
     if !res { fail!("Some tests failed"); }
 }
diff --git a/src/libstd/rt/test.rs b/src/libstd/rt/test.rs
index 4e2f9fbe130..2c293af1eaf 100644
--- a/src/libstd/rt/test.rs
+++ b/src/libstd/rt/test.rs
@@ -144,6 +144,12 @@ mod darwin_fd_limit {
     pub unsafe fn raise_fd_limit() {}
 }
 
+#[doc(hidden)]
+pub fn prepare_for_lots_of_tests() {
+    // Bump the fd limit on OS X. See darwin_fd_limit for an explanation.
+    unsafe { darwin_fd_limit::raise_fd_limit() }
+}
+
 /// Create more than one scheduler and run a function in a task
 /// in one of the schedulers. The schedulers will stay alive
 /// until the function `f` returns.
@@ -153,8 +159,8 @@ pub fn run_in_mt_newsched_task(f: ~fn()) {
     use rt::sched::Shutdown;
     use rt::util;
 
-    // Bump the fd limit on OS X. See darwin_fd_limit for an explanation.
-    unsafe { darwin_fd_limit::raise_fd_limit() }
+    // see comment in other function (raising fd limits)
+    prepare_for_lots_of_tests();
 
     let f = Cell::new(f);