diff --git a/benches/helpers/miri_helper.rs b/benches/helpers/miri_helper.rs
index 2bf78b0a71cc..0fbb46246aea 100644
--- a/benches/helpers/miri_helper.rs
+++ b/benches/helpers/miri_helper.rs
@@ -5,8 +5,7 @@ extern crate rustc_driver;
 extern crate test;
 
 use self::miri::eval_main;
-use self::rustc::session::Session;
-use self::rustc_driver::{driver, CompilerCalls, Compilation};
+use self::rustc_driver::{driver, Compilation};
 use std::cell::RefCell;
 use std::rc::Rc;
 use test::Bencher;
@@ -36,37 +35,26 @@ pub fn run(filename: &str, bencher: &mut Bencher) {
         "--sysroot".to_string(),
         find_sysroot(),
     ];
-    let compiler_calls = &mut MiriCompilerCalls(Rc::new(RefCell::new(bencher)));
-    rustc_driver::run_compiler(args, compiler_calls, None, None);
-}
+    let bencher = RefCell::new(bencher);
 
-impl<'a> CompilerCalls<'a> for MiriCompilerCalls<'a> {
-    fn build_controller(
-        &mut self,
-        _: &Session,
-        _: &getopts::Matches,
-    ) -> driver::CompileController<'a> {
-        let mut control: driver::CompileController<'a> = driver::CompileController::basic();
+    let mut control = driver::CompileController::basic();
 
-        let bencher = self.0.clone();
+    control.after_analysis.stop = Compilation::Stop;
+    control.after_analysis.callback = Box::new(move |state| {
+        state.session.abort_if_errors();
 
-        control.after_analysis.stop = Compilation::Stop;
-        control.after_analysis.callback = Box::new(move |state| {
-            state.session.abort_if_errors();
+        let tcx = state.tcx.unwrap();
+        let (entry_node_id, _, _) = state.session.entry_fn.borrow().expect(
+            "no main or start function found",
+        );
+        let entry_def_id = tcx.hir.local_def_id(entry_node_id);
 
-            let tcx = state.tcx.unwrap();
-            let (entry_node_id, _, _) = state.session.entry_fn.borrow().expect(
-                "no main or start function found",
-            );
-            let entry_def_id = tcx.hir.local_def_id(entry_node_id);
-
-            bencher.borrow_mut().iter(|| {
-                eval_main(tcx, entry_def_id, None);
-            });
-
-            state.session.abort_if_errors();
+        bencher.borrow_mut().iter(|| {
+            eval_main(tcx, entry_def_id, None);
         });
 
-        control
-    }
+        state.session.abort_if_errors();
+    });
+
+    rustc_driver::run_compiler(args, Box::new(control), None, None);
 }
diff --git a/rustc_tests/src/main.rs b/rustc_tests/src/main.rs
index ecc5287c7277..3e2cd032a80e 100644
--- a/rustc_tests/src/main.rs
+++ b/rustc_tests/src/main.rs
@@ -24,7 +24,7 @@ use rustc::ty::TyCtxt;
 use syntax::ast;
 
 struct MiriCompilerCalls {
-    default: RustcDefaultCalls,
+    default: Box<RustcDefaultCalls>,
     /// whether we are building for the host
     host_target: bool,
 }
@@ -63,11 +63,12 @@ impl<'a> CompilerCalls<'a> for MiriCompilerCalls {
     ) -> Compilation {
         self.default.late_callback(trans, matches, sess, cstore, input, odir, ofile)
     }
-    fn build_controller(&mut self, sess: &Session, matches: &getopts::Matches) -> CompileController<'a> {
-        let mut control = self.default.build_controller(sess, matches);
+    fn build_controller(self: Box<Self>, sess: &Session, matches: &getopts::Matches) -> CompileController<'a> {
+        let this = *self;
+        let mut control = this.default.build_controller(sess, matches);
         control.after_hir_lowering.callback = Box::new(after_hir_lowering);
         control.after_analysis.callback = Box::new(after_analysis);
-        if !self.host_target {
+        if !this.host_target {
             // only fully compile targets on the host
             control.after_analysis.stop = Compilation::Stop;
         }
@@ -182,10 +183,10 @@ fn main() {
         let buf = BufWriter::default();
         let output = buf.clone();
         let result = std::panic::catch_unwind(|| {
-            rustc_driver::run_compiler(&args, &mut MiriCompilerCalls {
-                default: RustcDefaultCalls,
+            rustc_driver::run_compiler(&args, Box::new(MiriCompilerCalls {
+                default: Box::new(RustcDefaultCalls),
                 host_target,
-            }, None, Some(Box::new(buf)));
+            }), None, Some(Box::new(buf)));
         });
 
         match result {
diff --git a/src/bin/miri.rs b/src/bin/miri.rs
index 8d80135cde30..35e83d49125e 100644
--- a/src/bin/miri.rs
+++ b/src/bin/miri.rs
@@ -23,7 +23,7 @@ use syntax::ast;
 use std::path::PathBuf;
 
 struct MiriCompilerCalls {
-    default: RustcDefaultCalls,
+    default: Box<RustcDefaultCalls>,
     /// Whether to begin interpretation at the start_fn lang item or not
     /// 
     /// If false, the interpretation begins at the `main` function
@@ -78,13 +78,14 @@ impl<'a> CompilerCalls<'a> for MiriCompilerCalls {
         self.default.late_callback(codegen_backend, matches, sess, cstore, input, odir, ofile)
     }
     fn build_controller(
-        &mut self,
+        self: Box<Self>,
         sess: &Session,
         matches: &getopts::Matches,
     ) -> CompileController<'a> {
-        let mut control = self.default.build_controller(sess, matches);
+        let this = *self;
+        let mut control = this.default.build_controller(sess, matches);
         control.after_hir_lowering.callback = Box::new(after_hir_lowering);
-        let start_fn = self.start_fn;
+        let start_fn = this.start_fn;
         control.after_analysis.callback = Box::new(move |state| after_analysis(state, start_fn));
         if sess.target.target != sess.host {
             // only fully compile targets on the host. linking will fail for cross-compilation.
@@ -234,8 +235,8 @@ fn main() {
     // Make sure we always have all the MIR (e.g. for auxilary builds in unit tests).
     args.push("-Zalways-encode-mir".to_owned());
 
-    rustc_driver::run_compiler(&args, &mut MiriCompilerCalls {
-        default: RustcDefaultCalls,
+    rustc_driver::run_compiler(&args, Box::new(MiriCompilerCalls {
+        default: Box::new(RustcDefaultCalls),
         start_fn,
-    }, None, None);
+    }), None, None);
 }
diff --git a/src/lib.rs b/src/lib.rs
index e8bbe164611d..d2ee39dd995a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -24,6 +24,7 @@ use rustc::ty::layout::{TyLayout, LayoutOf, Size};
 use rustc::ty::subst::Subst;
 use rustc::hir::def_id::DefId;
 use rustc::mir;
+use rustc::middle::const_val;
 
 use syntax::ast::Mutability;
 use syntax::codemap::Span;
@@ -253,9 +254,26 @@ pub fn eval_main<'a, 'tcx: 'a>(
                 //tcx.sess.err("the evaluated program leaked memory");
             }
         }
-        Err(mut e) => {
-            ecx.tcx.sess.err(&e.to_string());
-            ecx.report(&mut e, true, None);
+        Err(e) => {
+            if let Some(frame) = ecx.stack().last() {
+                let block = &frame.mir.basic_blocks()[frame.block];
+                let span = if frame.stmt < block.statements.len() {
+                    block.statements[frame.stmt].source_info.span
+                } else {
+                    block.terminator().source_info.span
+                };
+
+                let mut err = const_val::struct_error(ecx.tcx.tcx.at(span), "constant evaluation error");
+                let (frames, span) = ecx.generate_stacktrace(None);
+                err.span_label(span, e.to_string());
+                for const_val::FrameInfo { span, location, .. } in frames {
+                    err.span_note(span, &format!("inside call to `{}`", location));
+                }
+                err.emit();
+            } else {
+                ecx.tcx.sess.err(&e.to_string());
+            }
+
             for (i, frame) in ecx.stack().iter().enumerate() {
                 trace!("-------------------");
                 trace!("Frame {}", i);