diff --git a/src/test/incremental/hashes/extern_mods.rs b/src/test/incremental/hashes/extern_mods.rs
new file mode 100644
index 000000000000..03e621fedbeb
--- /dev/null
+++ b/src/test/incremental/hashes/extern_mods.rs
@@ -0,0 +1,272 @@
+// Copyright 2016 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.
+
+
+// This test case tests the incremental compilation hash (ICH) implementation
+// for `extern` modules.
+
+// The general pattern followed here is: Change one thing between rev1 and rev2
+// and make sure that the hash has changed, then change nothing between rev2 and
+// rev3 and make sure that the hash has not changed.
+
+// must-compile-successfully
+// revisions: cfail1 cfail2 cfail3
+// compile-flags: -Z query-dep-graph
+
+#![allow(warnings)]
+#![feature(rustc_attrs)]
+#![feature(unboxed_closures)]
+#![feature(link_args)]
+#![crate_type="rlib"]
+
+
+// Change function name --------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn change_function_name1(c: i64) -> i32;
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn change_function_name2(c: i64) -> i32;
+}
+
+
+
+// Change parameter name -------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn change_parameter_name(c: i64) -> i32;
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn change_parameter_name(d: i64) -> i32;
+}
+
+
+
+// Change parameter type -------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn change_parameter_type(c: i64) -> i32;
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn change_parameter_type(c: i32) -> i32;
+}
+
+
+
+// Change return type ----------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn change_return_type(c: i32) -> i32;
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn change_return_type(c: i32) -> i8;
+}
+
+
+
+// Add parameter ---------------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn add_parameter(c: i32) -> i32;
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn add_parameter(c: i32, d: i32) -> i32;
+}
+
+
+
+// Add return type -------------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn add_return_type(c: i32);
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn add_return_type(c: i32) -> i32;
+}
+
+
+
+// Make function variadic ------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn make_function_variadic(c: i32);
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn make_function_variadic(c: i32, ...);
+}
+
+
+
+// Change calling convention ---------------------------------------------------
+#[cfg(cfail1)]
+extern "C" {
+    pub fn change_calling_convention(c: i32);
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern "rust-call" {
+    pub fn change_calling_convention(c: i32);
+}
+
+
+
+// Make function public --------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    fn make_function_public(c: i32);
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn make_function_public(c: i32);
+}
+
+
+
+// Add function ----------------------------------------------------------------
+#[cfg(cfail1)]
+extern {
+    pub fn add_function1(c: i32);
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+extern {
+    pub fn add_function1(c: i32);
+    pub fn add_function2();
+}
+
+
+
+// Change link-args ------------------------------------------------------------
+#[cfg(cfail1)]
+#[link_args = "-foo -bar"]
+extern {
+    pub fn change_link_args(c: i32);
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+#[link_args = "-foo -bar -baz"]
+extern {
+    pub fn change_link_args(c: i32);
+}
+
+
+
+// Change link-name ------------------------------------------------------------
+#[cfg(cfail1)]
+#[link(name = "foo")]
+extern {
+    pub fn change_link_name(c: i32);
+}
+
+#[cfg(not(cfail1))]
+#[rustc_dirty(label="Hir", cfg="cfail2")]
+#[rustc_clean(label="Hir", cfg="cfail3")]
+#[rustc_metadata_dirty(cfg="cfail2")]
+#[rustc_metadata_clean(cfg="cfail3")]
+#[link(name = "bar")]
+extern {
+    pub fn change_link_name(c: i32);
+}
+
+type c_i32 = i32;
+type c_i64 = i64;
+
+// Indirectly change parameter type --------------------------------------------
+mod indirectly_change_parameter_type {
+    #[cfg(cfail1)]
+    use super::c_i32 as c_int;
+    #[cfg(not(cfail1))]
+    use super::c_i64 as c_int;
+
+    #[rustc_dirty(label="Hir", cfg="cfail2")]
+    #[rustc_clean(label="Hir", cfg="cfail3")]
+    #[rustc_metadata_dirty(cfg="cfail2")]
+    #[rustc_metadata_clean(cfg="cfail3")]
+    extern {
+        pub fn indirectly_change_parameter_type(c: c_int);
+    }
+}
+
+
+
+// Indirectly change return type --------------------------------------------
+mod indirectly_change_return_type {
+    #[cfg(cfail1)]
+    use super::c_i32 as c_int;
+    #[cfg(not(cfail1))]
+    use super::c_i64 as c_int;
+
+    #[rustc_dirty(label="Hir", cfg="cfail2")]
+    #[rustc_clean(label="Hir", cfg="cfail3")]
+    #[rustc_metadata_dirty(cfg="cfail2")]
+    #[rustc_metadata_clean(cfg="cfail3")]
+    extern {
+        pub fn indirectly_change_return_type() -> c_int;
+    }
+}