diff --git a/src/librustc_mir/borrow_check/nll/constraint_set.rs b/src/librustc_mir/borrow_check/nll/constraint_set.rs
index 154db25145e..cbef674b269 100644
--- a/src/librustc_mir/borrow_check/nll/constraint_set.rs
+++ b/src/librustc_mir/borrow_check/nll/constraint_set.rs
@@ -15,6 +15,7 @@ use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 
 use std::fmt;
 use syntax_pos::Span;
+use std::ops::Deref;
 
 #[derive(Clone, Default)]
 crate struct ConstraintSet {
@@ -37,10 +38,6 @@ impl ConstraintSet {
         }
     }
 
-    pub fn inner(&self) -> &IndexVec<ConstraintIndex, OutlivesConstraint> {
-        &self.constraints
-    }
-
     pub fn link(&mut self, len: usize) -> IndexVec<RegionVid, Option<ConstraintIndex>> {
         let mut map = IndexVec::from_elem_n(None, len);
 
@@ -66,6 +63,12 @@ impl ConstraintSet {
     }
 }
 
+impl Deref for ConstraintSet {
+    type Target = IndexVec<ConstraintIndex, OutlivesConstraint>;
+
+    fn deref(&self) -> &Self::Target { &self.constraints }
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct OutlivesConstraint {
     // NB. The ordering here is not significant for correctness, but
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/dump_mir.rs b/src/librustc_mir/borrow_check/nll/region_infer/dump_mir.rs
index b10e7cf21e9..6c796ea4c73 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/dump_mir.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/dump_mir.rs
@@ -76,7 +76,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             }
         }
 
-        let mut constraints: Vec<_> = self.constraints.inner().iter().collect();
+        let mut constraints: Vec<_> = self.constraints.iter().collect();
         constraints.sort();
         for constraint in &constraints {
             let OutlivesConstraint {
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/graphviz.rs b/src/librustc_mir/borrow_check/nll/region_infer/graphviz.rs
index f9c1b799c08..106dd003cea 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/graphviz.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/graphviz.rs
@@ -57,7 +57,7 @@ impl<'this, 'tcx> dot::GraphWalk<'this> for RegionInferenceContext<'tcx> {
         vids.into_cow()
     }
     fn edges(&'this self) -> dot::Edges<'this, OutlivesConstraint> {
-        (&self.constraints.inner().raw[..]).into_cow()
+        (&self.constraints.raw[..]).into_cow()
     }
 
     // Render `a: b` as `a <- b`, indicating the flow
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
index 488223e22e2..a576dc5f7f4 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
@@ -216,7 +216,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         type_tests: Vec<TypeTest<'tcx>>,
     ) -> Self {
         // The `next` field should not yet have been initialized:
-        debug_assert!(outlives_constraints.inner().iter().all(|c| c.next.is_none()));
+        debug_assert!(outlives_constraints.iter().all(|c| c.next.is_none()));
 
         let num_region_variables = var_infos.len();
         let num_universal_regions = universal_regions.len();
@@ -438,7 +438,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     fn compute_region_values(&self, _mir: &Mir<'tcx>) -> RegionValues {
         debug!("compute_region_values()");
         debug!("compute_region_values: constraints={:#?}", {
-            let mut constraints: Vec<_> = self.constraints.inner().iter().collect();
+            let mut constraints: Vec<_> = self.constraints.iter().collect();
             constraints.sort();
             constraints
         });
@@ -450,7 +450,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let dependency_map = self.dependency_map.as_ref().unwrap();
 
         // Constraints that may need to be repropagated (initially all):
-        let mut dirty_list: Vec<_> = self.constraints.inner().indices().collect();
+        let mut dirty_list: Vec<_> = self.constraints.indices().collect();
 
         // Set to 0 for each constraint that is on the dirty list:
         let mut clean_bit_vec = BitVector::new(dirty_list.len());
@@ -459,7 +459,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         while let Some(constraint_idx) = dirty_list.pop() {
             clean_bit_vec.insert(constraint_idx.index());
 
-            let constraint = &self.constraints.inner()[constraint_idx];
+            let constraint = &self.constraints[constraint_idx];
             debug!("propagate_constraints: constraint={:?}", constraint);
 
             if inferred_values.add_region(constraint.sup, constraint.sub) {
@@ -925,7 +925,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             );
 
             let blame_index = self.blame_constraint(longer_fr, shorter_fr);
-            let blame_span = self.constraints.inner()[blame_index].span;
+            let blame_span = self.constraints[blame_index].span;
 
             if let Some(propagated_outlives_requirements) = propagated_outlives_requirements {
                 // Shrink `fr` until we find a non-local region (if we do).
@@ -1016,7 +1016,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // - `fr1: X` transitively
         // - and `Y` is live at `elem`
         let index = self.blame_constraint(fr1, elem);
-        let region_sub = self.constraints.inner()[index].sub;
+        let region_sub = self.constraints[index].sub;
 
         // then return why `Y` was live at `elem`
         self.liveness_constraints.cause(region_sub, elem)
@@ -1037,7 +1037,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         // of dependencies, which doesn't account for the locations of
         // contraints at all. But it will do for now.
         let relevant_constraint = self.constraints
-            .inner()
             .iter_enumerated()
             .filter_map(|(i, constraint)| {
                 if !self.liveness_constraints.contains(constraint.sub, elem) {
@@ -1073,7 +1072,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
         while changed {
             changed = false;
-            for constraint in self.constraints.inner() {
+            for constraint in self.constraints.iter() {
                 if let Some(n) = result_set[constraint.sup] {
                     let m = n + 1;
                     if result_set[constraint.sub]