diff --git a/src/libcore/core.rc b/src/libcore/core.rc
index a90758694f83a..ef88258daec59 100644
--- a/src/libcore/core.rc
+++ b/src/libcore/core.rc
@@ -41,6 +41,10 @@ export either, option, result, iter;
 export libc, os, io, run, rand, sys, unsafe, logging;
 export arc, comm, task, future, pipes;
 export extfmt;
+// The test harness links against core, so don't include runtime in tests.
+// FIXME (#2861): Uncomment this after snapshot gets updated.
+//#[cfg(notest)]
+export rt;
 export tuple;
 export to_str, to_bytes;
 export dvec, dvec_iter;
@@ -206,6 +210,9 @@ mod unsafe;
 // Exported but not part of the public interface
 
 mod extfmt;
+// The test harness links against core, so don't include runtime in tests.
+#[cfg(notest)]
+mod rt;
 
 
 // For internal use, not exported
diff --git a/src/libcore/rt.rs b/src/libcore/rt.rs
new file mode 100644
index 0000000000000..a588aab9b68ec
--- /dev/null
+++ b/src/libcore/rt.rs
@@ -0,0 +1,27 @@
+//! Runtime calls emitted by the compiler.
+
+import libc::c_char;
+import libc::size_t;
+
+type rust_task = libc::c_void;
+
+extern mod rustrt {
+    #[rust_stack]
+    fn rust_upcall_fail(expr: *c_char, file: *c_char, line: size_t);
+}
+
+// FIXME (#2861): This needs both the attribute, and the name prefixed with
+// 'rt_', otherwise the compiler won't find it. To fix this, see
+// gather_rust_rtcalls.
+#[rt(fail)]
+fn rt_fail(expr: *c_char, file: *c_char, line: size_t) {
+    rustrt::rust_upcall_fail(expr, file, line);
+}
+
+// Local Variables:
+// mode: rust;
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// End:
diff --git a/src/rt/rust_upcall.cpp b/src/rt/rust_upcall.cpp
index cae5ce45b5497..736ee84196579 100644
--- a/src/rt/rust_upcall.cpp
+++ b/src/rt/rust_upcall.cpp
@@ -98,6 +98,16 @@ upcall_fail(char const *expr,
     UPCALL_SWITCH_STACK(task, &args, upcall_s_fail);
 }
 
+// FIXME (#2861): Alias used by libcore/rt.rs to avoid naming conflicts with
+// autogenerated wrappers for upcall_fail. Remove this when we fully move away
+// away from the C upcall path.
+extern "C" CDECL void
+rust_upcall_fail(char const *expr,
+                 char const *file,
+                 size_t line) {
+    upcall_fail(expr, file, line);
+}
+
 struct s_trace_args {
     rust_task *task;
     char const *msg;
diff --git a/src/rustc/driver/driver.rs b/src/rustc/driver/driver.rs
index 1222cfc2d6085..52aa88e6cb639 100644
--- a/src/rustc/driver/driver.rs
+++ b/src/rustc/driver/driver.rs
@@ -69,10 +69,11 @@ fn build_configuration(sess: session, argv0: ~str, input: input) ->
     // If the user wants a test runner, then add the test cfg
     let gen_cfg =
         {
-            if sess.opts.test && !attr::contains_name(user_cfg, ~"test")
-               {
+            if sess.opts.test && !attr::contains_name(user_cfg, ~"test") {
                 ~[attr::mk_word_item(@~"test")]
-            } else { ~[] }
+            } else {
+                ~[attr::mk_word_item(@~"notest")]
+            }
         };
     ret vec::append(vec::append(user_cfg, gen_cfg), default_cfg);
 }
diff --git a/src/rustc/middle/trans/base.rs b/src/rustc/middle/trans/base.rs
index 951bcce910f08..b4f6b57a86bfd 100644
--- a/src/rustc/middle/trans/base.rs
+++ b/src/rustc/middle/trans/base.rs
@@ -37,7 +37,7 @@ import link::{mangle_internal_name_by_type_only,
               mangle_internal_name_by_path,
               mangle_internal_name_by_path_and_seq,
               mangle_exported_name};
-import metadata::{csearch, cstore, encoder};
+import metadata::{csearch, cstore, decoder, encoder};
 import metadata::common::link_meta;
 import util::ppaux;
 import util::ppaux::{ty_to_str, ty_to_short_str};
@@ -3942,11 +3942,25 @@ fn trans_fail_value(bcx: block, sp_opt: option<span>,
     let V_str = PointerCast(bcx, V_fail_str, T_ptr(T_i8()));
     let V_filename = PointerCast(bcx, V_filename, T_ptr(T_i8()));
     let args = ~[V_str, V_filename, C_int(ccx, V_line)];
-    let bcx = invoke(bcx, bcx.ccx().upcalls._fail, args);
+    let bcx = trans_rtcall(bcx, ~"fail", args);
     Unreachable(bcx);
     ret bcx;
 }
 
+fn trans_rtcall(bcx: block, name: ~str, args: ~[ValueRef]) -> block {
+    let did = bcx.ccx().rtcalls[name];
+    let fty = if did.crate == ast::local_crate {
+        ty::node_id_to_type(bcx.ccx().tcx, did.node)
+    } else {
+        csearch::get_type(bcx.ccx().tcx, did).ty
+    };
+    let rty = ty::ty_fn_ret(fty);
+    ret trans_call_inner(
+        bcx, none, fty, rty,
+        |bcx| lval_static_fn_inner(bcx, did, 0, ~[], none),
+        arg_vals(args), ignore);
+}
+
 fn trans_break_cont(bcx: block, to_end: bool)
     -> block {
     let _icx = bcx.insn_ctxt(~"trans_break_cont");
@@ -5314,6 +5328,79 @@ fn trap(bcx: block) {
     }
 }
 
+fn push_rtcall(ccx: @crate_ctxt, name: ~str, did: ast::def_id) {
+    if ccx.rtcalls.contains_key(name) {
+        fail #fmt("multiple definitions for runtime call %s", name);
+    }
+    ccx.rtcalls.insert(name, did);
+}
+
+fn gather_local_rtcalls(ccx: @crate_ctxt, crate: @ast::crate) {
+    visit::visit_crate(*crate, (), visit::mk_simple_visitor(@{
+        visit_item: |item| alt item.node {
+          ast::item_fn(decl, _, _) {
+            let attr_metas = attr::attr_metas(
+                attr::find_attrs_by_name(item.attrs, ~"rt"));
+            do vec::iter(attr_metas) |attr_meta| {
+                alt attr::get_meta_item_list(attr_meta) {
+                  some(list) {
+                    let name = *attr::get_meta_item_name(vec::head(list));
+                    push_rtcall(ccx, name, {crate: ast::local_crate,
+                                            node: item.id});
+                  }
+                  none {}
+                }
+            }
+          }
+          _ {}
+        }
+        with *visit::default_simple_visitor()
+    }));
+}
+
+fn gather_external_rtcalls(ccx: @crate_ctxt) {
+    do cstore::iter_crate_data(ccx.sess.cstore) |_cnum, cmeta| {
+        do decoder::each_path(cmeta) |path| {
+            let pathname = path.path_string;
+            alt path.def_like {
+              decoder::dl_def(d) {
+                alt d {
+                  ast::def_fn(did, _) {
+                    // FIXME (#2861): This should really iterate attributes
+                    // like gather_local_rtcalls, but we'll need to
+                    // export attributes in metadata/encoder before we can do
+                    // that.
+                    let sentinel = "rt::rt_";
+                    let slen = str::len(sentinel);
+                    if str::starts_with(pathname, sentinel) {
+                        let name = str::substr(pathname,
+                                               slen, str::len(pathname)-slen);
+                        push_rtcall(ccx, name, did);
+                    }
+                  }
+                  _ {}
+                }
+              }
+              _ {}
+            }
+            true
+        }
+    }
+}
+
+fn gather_rtcalls(ccx: @crate_ctxt, crate: @ast::crate) {
+    gather_local_rtcalls(ccx, crate);
+    gather_external_rtcalls(ccx);
+
+    // FIXME (#2861): Check for other rtcalls too, once they are
+    // supported. Also probably want to check type signature so we don't crash
+    // in some obscure place in LLVM if the user provides the wrong signature
+    // for an rtcall.
+    if !ccx.rtcalls.contains_key(~"fail") {
+        fail ~"no definition for runtime call fail";
+    }
+}
+
 fn create_module_map(ccx: @crate_ctxt) -> ValueRef {
     let elttype = T_struct(~[ccx.int_type, ccx.int_type]);
     let maptype = T_array(elttype, ccx.module_data.size() + 1u);
@@ -5544,6 +5631,7 @@ fn trans_crate(sess: session::session, crate: @ast::crate, tcx: ty::ctxt,
           upcalls:
               upcall::declare_upcalls(targ_cfg, tn, tydesc_type,
                                       llmod),
+          rtcalls: str_hash::<ast::def_id>(),
           tydesc_type: tydesc_type,
           int_type: int_type,
           float_type: float_type,
@@ -5557,6 +5645,8 @@ fn trans_crate(sess: session::session, crate: @ast::crate, tcx: ty::ctxt,
           mut do_not_commit_warning_issued: false};
 
 
+    gather_rtcalls(ccx, crate);
+
     {
         let _icx = ccx.insn_ctxt(~"data");
         trans_constants(ccx, crate);
diff --git a/src/rustc/middle/trans/common.rs b/src/rustc/middle/trans/common.rs
index 77929bdd6a3c5..c002c5a2a43c9 100644
--- a/src/rustc/middle/trans/common.rs
+++ b/src/rustc/middle/trans/common.rs
@@ -118,6 +118,7 @@ type crate_ctxt = {
      maps: astencode::maps,
      stats: stats,
      upcalls: @upcall::upcalls,
+     rtcalls: hashmap<~str, ast::def_id>,
      tydesc_type: TypeRef,
      int_type: TypeRef,
      float_type: TypeRef,
diff --git a/src/test/run-pass/module-polymorphism.rc b/src/test/run-pass/module-polymorphism.rc
index 781e3a279b194..3f93608e53add 100644
--- a/src/test/run-pass/module-polymorphism.rc
+++ b/src/test/run-pass/module-polymorphism.rc
@@ -1,8 +1,5 @@
-#[no_core];
-
-
 #[path = "module-polymorphism-files"]
-mod float {
+mod my_float {
 
     // The type of the float
     import inst::T;
@@ -18,7 +15,7 @@ mod float {
 }
 
 #[path = "module-polymorphism-files"]
-mod f64 {
+mod my_f64 {
 
     import inst::T;
 
@@ -33,7 +30,7 @@ mod f64 {
 }
 
 #[path = "module-polymorphism-files"]
-mod f32 {
+mod my_f32 {
     import inst::T;
 
     #[path = "inst_f32.rs"]
diff --git a/src/test/run-pass/module-polymorphism.rs b/src/test/run-pass/module-polymorphism.rs
index e2f8350ef72af..26c3582d6a635 100644
--- a/src/test/run-pass/module-polymorphism.rs
+++ b/src/test/run-pass/module-polymorphism.rs
@@ -5,7 +5,7 @@
 fn main() {
     // All of these functions are defined by a single module
     // source file but instantiated for different types
-    assert float::template::plus(1.0f, 2.0f) == 3.0f;
-    assert f64::template::plus(1.0f64, 2.0f64) == 3.0f64;
-    assert f32::template::plus(1.0f32, 2.0f32) == 3.0f32;
+    assert my_float::template::plus(1.0f, 2.0f) == 3.0f;
+    assert my_f64::template::plus(1.0f64, 2.0f64) == 3.0f64;
+    assert my_f32::template::plus(1.0f32, 2.0f32) == 3.0f32;
 }
\ No newline at end of file
diff --git a/src/test/run-pass/module-polymorphism2.rc b/src/test/run-pass/module-polymorphism2.rc
index 0d64cb46a2672..bc801bcb4a3f2 100644
--- a/src/test/run-pass/module-polymorphism2.rc
+++ b/src/test/run-pass/module-polymorphism2.rc
@@ -1,6 +1,3 @@
-#[no_core];
-
-
 #[path = "module-polymorphism2-files"]
 mod mystd {
 
diff --git a/src/test/run-pass/module-polymorphism3.rc b/src/test/run-pass/module-polymorphism3.rc
index 34dc9000e3236..3ed7be15ff5fa 100644
--- a/src/test/run-pass/module-polymorphism3.rc
+++ b/src/test/run-pass/module-polymorphism3.rc
@@ -1,5 +1,3 @@
-#[no_core];
-
 // Use one template module to specify in a single file the implementation
 // of functions for multiple types