diff --git a/src/librustc_mir/borrow_check/region_infer/mod.rs b/src/librustc_mir/borrow_check/region_infer/mod.rs
index 43744d782192a..089a9b7328eb1 100644
--- a/src/librustc_mir/borrow_check/region_infer/mod.rs
+++ b/src/librustc_mir/borrow_check/region_infer/mod.rs
@@ -113,7 +113,7 @@ pub struct RegionInferenceContext<'tcx> {
 
     /// Information about how the universally quantified regions in
     /// scope on this function relate to one another.
-    universal_region_relations: Rc<UniversalRegionRelations<'tcx>>,
+    universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
 }
 
 /// Each time that `apply_member_constraint` is successful, it appends
@@ -243,11 +243,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ///
     /// The `outlives_constraints` and `type_tests` are an initial set
     /// of constraints produced by the MIR type check.
-    pub(crate) fn new(
+    pub(in crate::borrow_check) fn new(
         var_infos: VarInfos,
         universal_regions: Rc<UniversalRegions<'tcx>>,
         placeholder_indices: Rc<PlaceholderIndices>,
-        universal_region_relations: Rc<UniversalRegionRelations<'tcx>>,
+        universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
         outlives_constraints: OutlivesConstraintSet,
         member_constraints_in: MemberConstraintSet<'tcx, RegionVid>,
         closure_bounds_mapping: FxHashMap<
diff --git a/src/librustc_mir/borrow_check/type_check/free_region_relations.rs b/src/librustc_mir/borrow_check/type_check/free_region_relations.rs
index 137216531a369..a18004ce1918a 100644
--- a/src/librustc_mir/borrow_check/type_check/free_region_relations.rs
+++ b/src/librustc_mir/borrow_check/type_check/free_region_relations.rs
@@ -15,6 +15,7 @@ use crate::borrow_check::{
     type_check::constraint_conversion,
     type_check::{Locations, MirTypeckRegionConstraints},
     universal_regions::UniversalRegions,
+    Frozen,
 };
 
 #[derive(Debug)]
@@ -52,7 +53,7 @@ type RegionBoundPairs<'tcx> = Vec<(ty::Region<'tcx>, GenericKind<'tcx>)>;
 type NormalizedInputsAndOutput<'tcx> = Vec<Ty<'tcx>>;
 
 crate struct CreateResult<'tcx> {
-    crate universal_region_relations: Rc<UniversalRegionRelations<'tcx>>,
+    pub(in crate::borrow_check) universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
     crate region_bound_pairs: RegionBoundPairs<'tcx>,
     crate normalized_inputs_and_output: NormalizedInputsAndOutput<'tcx>,
 }
@@ -297,7 +298,7 @@ impl UniversalRegionRelationsBuilder<'cx, 'tcx> {
         }
 
         CreateResult {
-            universal_region_relations: Rc::new(self.relations),
+            universal_region_relations: Frozen::freeze(self.relations),
             region_bound_pairs: self.region_bound_pairs,
             normalized_inputs_and_output,
         }
diff --git a/src/librustc_mir/borrow_check/type_check/mod.rs b/src/librustc_mir/borrow_check/type_check/mod.rs
index ace92949814a7..f4656673fec62 100644
--- a/src/librustc_mir/borrow_check/type_check/mod.rs
+++ b/src/librustc_mir/borrow_check/type_check/mod.rs
@@ -55,6 +55,7 @@ use crate::borrow_check::{
     renumber,
     type_check::free_region_relations::{CreateResult, UniversalRegionRelations},
     universal_regions::{DefiningTy, UniversalRegions},
+    Frozen,
 };
 
 macro_rules! span_mirbug {
@@ -828,7 +829,7 @@ struct BorrowCheckContext<'a, 'tcx> {
 
 crate struct MirTypeckResults<'tcx> {
     crate constraints: MirTypeckRegionConstraints<'tcx>,
-    crate universal_region_relations: Rc<UniversalRegionRelations<'tcx>>,
+    pub(in crate::borrow_check) universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
     crate opaque_type_values: FxHashMap<DefId, ty::ResolvedOpaqueTy<'tcx>>,
 }