diff --git a/src/test/auxiliary/unboxed-closures-cross-crate.rs b/src/test/auxiliary/unboxed-closures-cross-crate.rs
new file mode 100644
index 00000000000..d04829bb808
--- /dev/null
+++ b/src/test/auxiliary/unboxed-closures-cross-crate.rs
@@ -0,0 +1,26 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(unboxed_closures, overloaded_calls)]
+
+#[inline]
+pub fn has_closures() -> uint {
+    let x = 1u;
+    let mut f = move |&mut:| x;
+    let y = 1u;
+    let g = |:| y;
+    f() + g()
+}
+
+pub fn has_generic_closures<T: Add<T,T> + Copy>(x: T, y: T) -> T {
+    let mut f = move |&mut:| x;
+    let g = |:| y;
+    f() + g()
+}
diff --git a/src/test/run-pass/unboxed-closures-cross-crate.rs b/src/test/run-pass/unboxed-closures-cross-crate.rs
new file mode 100644
index 00000000000..3babaa2b7e5
--- /dev/null
+++ b/src/test/run-pass/unboxed-closures-cross-crate.rs
@@ -0,0 +1,20 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Test that unboxed closures work with cross-crate inlining
+// Acts as a regression test for #16790, #18378 and #18543
+
+// aux-build:unboxed-closures-cross-crate.rs
+extern crate "unboxed-closures-cross-crate" as ubcc;
+
+fn main() {
+    assert_eq!(ubcc::has_closures(), 2u);
+    assert_eq!(ubcc::has_generic_closures(2u, 3u), 5u);
+}