diff --git a/src/librustc/ich/impls_ty.rs b/src/librustc/ich/impls_ty.rs
index 9a442e0529938..594adfca6b3c0 100644
--- a/src/librustc/ich/impls_ty.rs
+++ b/src/librustc/ich/impls_ty.rs
@@ -1111,7 +1111,6 @@ for ty::steal::Steal<T>
 
 impl_stable_hash_for!(struct ty::ParamEnv<'tcx> {
     caller_bounds,
-    universe,
     reveal
 });
 
@@ -1282,15 +1281,6 @@ for traits::VtableGeneratorData<'gcx, N> where N: HashStable<StableHashingContex
     }
 }
 
-impl<'a> HashStable<StableHashingContext<'a>>
-for ty::UniverseIndex {
-    fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'a>,
-                                          hasher: &mut StableHasher<W>) {
-        self.depth().hash_stable(hcx, hasher);
-    }
-}
-
 impl_stable_hash_for!(
     impl<'tcx, V> for struct infer::canonical::Canonical<'tcx, V> {
         variables, value
diff --git a/src/librustc/infer/anon_types/mod.rs b/src/librustc/infer/anon_types/mod.rs
index 93e8745af1b57..eb5df697216a3 100644
--- a/src/librustc/infer/anon_types/mod.rs
+++ b/src/librustc/infer/anon_types/mod.rs
@@ -726,10 +726,7 @@ impl<'a, 'gcx, 'tcx> Instantiator<'a, 'gcx, 'tcx> {
             return anon_defn.concrete_ty;
         }
         let span = tcx.def_span(def_id);
-        let ty_var = infcx.next_ty_var(
-            ty::UniverseIndex::ROOT,
-            TypeVariableOrigin::TypeInference(span),
-        );
+        let ty_var = infcx.next_ty_var(TypeVariableOrigin::TypeInference(span));
 
         let predicates_of = tcx.predicates_of(def_id);
         let bounds = predicates_of.instantiate(tcx, substs);
diff --git a/src/librustc/infer/canonical.rs b/src/librustc/infer/canonical.rs
index debddd708ea22..4357c9a5a776a 100644
--- a/src/librustc/infer/canonical.rs
+++ b/src/librustc/infer/canonical.rs
@@ -254,8 +254,6 @@ impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
                 let ty = match ty_kind {
                     CanonicalTyVarKind::General => {
                         self.next_ty_var(
-                            // FIXME(#48696) this handling of universes is not right.
-                            ty::UniverseIndex::ROOT,
                             TypeVariableOrigin::MiscVariable(span),
                         )
                     }
diff --git a/src/librustc/infer/combine.rs b/src/librustc/infer/combine.rs
index 1c581c44464e7..c2167751a27e7 100644
--- a/src/librustc/infer/combine.rs
+++ b/src/librustc/infer/combine.rs
@@ -407,7 +407,7 @@ impl<'cx, 'gcx, 'tcx> TypeRelation<'cx, 'gcx, 'tcx> for Generalizer<'cx, 'gcx, '
                             drop(variables);
                             self.relate(&u, &u)
                         }
-                        TypeVariableValue::Unknown { universe } => {
+                        TypeVariableValue::Unknown { .. } => {
                             match self.ambient_variance {
                                 // Invariant: no need to make a fresh type variable.
                                 ty::Invariant => return Ok(t),
@@ -424,7 +424,7 @@ impl<'cx, 'gcx, 'tcx> TypeRelation<'cx, 'gcx, 'tcx> for Generalizer<'cx, 'gcx, '
                             }
 
                             let origin = *variables.var_origin(vid);
-                            let new_var_id = variables.new_var(universe, false, origin);
+                            let new_var_id = variables.new_var(false, origin);
                             let u = self.tcx().mk_var(new_var_id);
                             debug!("generalize: replacing original vid={:?} with new={:?}",
                                    vid, u);
diff --git a/src/librustc/infer/fudge.rs b/src/librustc/infer/fudge.rs
index 48eb253415cdf..961dd70a46852 100644
--- a/src/librustc/infer/fudge.rs
+++ b/src/librustc/infer/fudge.rs
@@ -141,11 +141,7 @@ impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for RegionFudger<'a, 'gcx, 'tcx> {
                         // This variable was created during the
                         // fudging. Recreate it with a fresh variable
                         // here.
-                        //
-                        // The ROOT universe is fine because we only
-                        // ever invoke this routine at the
-                        // "item-level" of inference.
-                        self.infcx.next_ty_var(ty::UniverseIndex::ROOT, origin)
+                        self.infcx.next_ty_var(origin)
                     }
                 }
             }
diff --git a/src/librustc/infer/lattice.rs b/src/librustc/infer/lattice.rs
index c4722f9a7f96c..28aba51ab3724 100644
--- a/src/librustc/infer/lattice.rs
+++ b/src/librustc/infer/lattice.rs
@@ -88,17 +88,13 @@ pub fn super_lattice_tys<'a, 'gcx, 'tcx, L>(this: &mut L,
         // is (e.g.) `Box<i32>`. A more obvious solution might be to
         // iterate on the subtype obligations that are returned, but I
         // think this suffices. -nmatsakis
-        (&ty::TyInfer(TyVar(a_vid)), _) => {
-            let universe = infcx.type_variables.borrow_mut().probe(a_vid).universe().unwrap();
-            let v = infcx.next_ty_var(universe,
-                                      TypeVariableOrigin::LatticeVariable(this.cause().span));
+        (&ty::TyInfer(TyVar(..)), _) => {
+            let v = infcx.next_ty_var(TypeVariableOrigin::LatticeVariable(this.cause().span));
             this.relate_bound(v, b, a)?;
             Ok(v)
         }
-        (_, &ty::TyInfer(TyVar(b_vid))) => {
-            let universe = infcx.type_variables.borrow_mut().probe(b_vid).universe().unwrap();
-            let v = infcx.next_ty_var(universe,
-                                      TypeVariableOrigin::LatticeVariable(this.cause().span));
+        (_, &ty::TyInfer(TyVar(..))) => {
+            let v = infcx.next_ty_var(TypeVariableOrigin::LatticeVariable(this.cause().span));
             this.relate_bound(v, a, b)?;
             Ok(v)
         }
diff --git a/src/librustc/infer/mod.rs b/src/librustc/infer/mod.rs
index fe919775da0b4..032a5c59d2dca 100644
--- a/src/librustc/infer/mod.rs
+++ b/src/librustc/infer/mod.rs
@@ -837,25 +837,18 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         })
     }
 
-    pub fn next_ty_var_id(&self,
-                          universe: ty::UniverseIndex,
-                          diverging: bool,
-                          origin: TypeVariableOrigin)
-                          -> TyVid {
+    pub fn next_ty_var_id(&self, diverging: bool, origin: TypeVariableOrigin) -> TyVid {
         self.type_variables
             .borrow_mut()
-            .new_var(universe, diverging, origin)
+            .new_var(diverging, origin)
     }
 
-    pub fn next_ty_var(&self, universe: ty::UniverseIndex, origin: TypeVariableOrigin) -> Ty<'tcx> {
-        self.tcx.mk_var(self.next_ty_var_id(universe, false, origin))
+    pub fn next_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
+        self.tcx.mk_var(self.next_ty_var_id(false, origin))
     }
 
-    pub fn next_diverging_ty_var(&self,
-                                 universe: ty::UniverseIndex,
-                                 origin: TypeVariableOrigin)
-                                 -> Ty<'tcx> {
-        self.tcx.mk_var(self.next_ty_var_id(universe, true, origin))
+    pub fn next_diverging_ty_var(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
+        self.tcx.mk_var(self.next_ty_var_id(true, origin))
     }
 
     pub fn next_int_var_id(&self) -> IntVid {
@@ -910,14 +903,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     /// use an inference variable for `C` with `[T, U]`
     /// as the substitutions for the default, `(T, U)`.
     pub fn type_var_for_def(&self,
-                            universe: ty::UniverseIndex,
                             span: Span,
                             def: &ty::TypeParameterDef)
                             -> Ty<'tcx> {
         let ty_var_id = self.type_variables
                             .borrow_mut()
-                            .new_var(universe,
-                                     false,
+                            .new_var(false,
                                      TypeVariableOrigin::TypeParameterDefinition(span, def.name));
 
         self.tcx.mk_var(ty_var_id)
@@ -926,14 +917,13 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     /// Given a set of generics defined on a type or impl, returns a substitution mapping each
     /// type/region parameter to a fresh inference variable.
     pub fn fresh_substs_for_item(&self,
-                                 universe: ty::UniverseIndex,
                                  span: Span,
                                  def_id: DefId)
                                  -> &'tcx Substs<'tcx> {
         Substs::for_item(self.tcx, def_id, |def, _| {
             self.region_var_for_def(span, def)
         }, |def, _| {
-            self.type_var_for_def(universe, span, def)
+            self.type_var_for_def(span, def)
         })
     }
 
diff --git a/src/librustc/infer/region_constraints/mod.rs b/src/librustc/infer/region_constraints/mod.rs
index e864485539b2d..4113a2dd4178b 100644
--- a/src/librustc/infer/region_constraints/mod.rs
+++ b/src/librustc/infer/region_constraints/mod.rs
@@ -48,7 +48,7 @@ pub struct RegionConstraintCollector<'tcx> {
     glbs: CombineMap<'tcx>,
 
     /// Number of skolemized variables currently active.
-    skolemization_count: ty::UniverseIndex,
+    skolemization_count: u32,
 
     /// Global counter used during the GLB algorithm to create unique
     /// names for fresh bound regions
@@ -233,7 +233,7 @@ type CombineMap<'tcx> = FxHashMap<TwoRegions<'tcx>, RegionVid>;
 pub struct RegionSnapshot {
     length: usize,
     region_snapshot: ut::Snapshot<ut::InPlace<ty::RegionVid>>,
-    skolemization_count: ty::UniverseIndex,
+    skolemization_count: u32,
 }
 
 /// When working with skolemized regions, we often wish to find all of
@@ -277,7 +277,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
             data: RegionConstraintData::default(),
             lubs: FxHashMap(),
             glbs: FxHashMap(),
-            skolemization_count: ty::UniverseIndex::ROOT,
+            skolemization_count: 0,
             bound_count: 0,
             undo_log: Vec::new(),
             unification_table: ut::UnificationTable::new(),
@@ -329,7 +329,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
             unification_table,
         } = self;
 
-        assert_eq!(skolemization_count.as_usize(), 0);
+        assert_eq!(*skolemization_count, 0);
 
         // Clear the tables of (lubs, glbs), so that we will create
         // fresh regions if we do a LUB operation. As it happens,
@@ -375,7 +375,7 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
         assert!(self.undo_log[snapshot.length] == OpenSnapshot);
         assert!(
             self.skolemization_count == snapshot.skolemization_count,
-            "failed to pop skolemized regions: {:?} now vs {:?} at start",
+            "failed to pop skolemized regions: {} now vs {} at start",
             self.skolemization_count,
             snapshot.skolemization_count
         );
@@ -485,9 +485,9 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
         assert!(self.in_snapshot());
         assert!(self.undo_log[snapshot.length] == OpenSnapshot);
 
-        let universe = self.skolemization_count.subuniverse();
-        self.skolemization_count = universe;
-        tcx.mk_region(ReSkolemized(universe, br))
+        let sc = self.skolemization_count;
+        self.skolemization_count = sc + 1;
+        tcx.mk_region(ReSkolemized(ty::SkolemizedRegionVid { index: sc }, br))
     }
 
     /// Removes all the edges to/from the skolemized regions that are
@@ -505,20 +505,20 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
         assert!(self.in_snapshot());
         assert!(self.undo_log[snapshot.length] == OpenSnapshot);
         assert!(
-            self.skolemization_count.as_usize() >= skols.len(),
+            self.skolemization_count as usize >= skols.len(),
             "popping more skolemized variables than actually exist, \
              sc now = {}, skols.len = {}",
-            self.skolemization_count.as_usize(),
+            self.skolemization_count,
             skols.len()
         );
 
-        let last_to_pop = self.skolemization_count.subuniverse();
-        let first_to_pop = ty::UniverseIndex::from(last_to_pop.as_u32() - (skols.len() as u32));
+        let last_to_pop = self.skolemization_count;
+        let first_to_pop = last_to_pop - (skols.len() as u32);
 
         assert!(
             first_to_pop >= snapshot.skolemization_count,
             "popping more regions than snapshot contains, \
-             sc now = {:?}, sc then = {:?}, skols.len = {}",
+             sc now = {}, sc then = {}, skols.len = {}",
             self.skolemization_count,
             snapshot.skolemization_count,
             skols.len()
@@ -526,13 +526,13 @@ impl<'tcx> RegionConstraintCollector<'tcx> {
         debug_assert! {
             skols.iter()
                  .all(|&k| match *k {
-                     ty::ReSkolemized(universe, _) =>
-                         universe >= first_to_pop &&
-                         universe < last_to_pop,
+                     ty::ReSkolemized(index, _) =>
+                         index.index >= first_to_pop &&
+                         index.index < last_to_pop,
                      _ =>
                          false
                  }),
-            "invalid skolemization keys or keys out of range ({:?}..{:?}): {:?}",
+            "invalid skolemization keys or keys out of range ({}..{}): {:?}",
             snapshot.skolemization_count,
             self.skolemization_count,
             skols
@@ -867,7 +867,7 @@ impl fmt::Debug for RegionSnapshot {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(
             f,
-            "RegionSnapshot(length={},skolemization={:?})",
+            "RegionSnapshot(length={},skolemization={})",
             self.length,
             self.skolemization_count
         )
diff --git a/src/librustc/infer/type_variable.rs b/src/librustc/infer/type_variable.rs
index 66360ea50bbe0..91df6cabf3a8b 100644
--- a/src/librustc/infer/type_variable.rs
+++ b/src/librustc/infer/type_variable.rs
@@ -78,18 +78,10 @@ struct TypeVariableData {
 #[derive(Copy, Clone, Debug)]
 pub enum TypeVariableValue<'tcx> {
     Known { value: Ty<'tcx> },
-    Unknown { universe: ty::UniverseIndex },
-}
-
-#[derive(Copy, Clone, Debug)]
-pub enum ProbeTyValue<'tcx> {
-    Ty(Ty<'tcx>),
-    Vid(ty::TyVid),
+    Unknown,
 }
 
 impl<'tcx> TypeVariableValue<'tcx> {
-    /// If this value is known, returns the type it is known to be.
-    /// Otherwise, `None`.
     pub fn known(&self) -> Option<Ty<'tcx>> {
         match *self {
             TypeVariableValue::Unknown { .. } => None,
@@ -97,14 +89,6 @@ impl<'tcx> TypeVariableValue<'tcx> {
         }
     }
 
-    /// If this value is unknown, returns the universe, otherwise `None`.
-    pub fn universe(&self) -> Option<ty::UniverseIndex> {
-        match *self {
-            TypeVariableValue::Unknown { universe } => Some(universe),
-            TypeVariableValue::Known { .. } => None,
-        }
-    }
-
     pub fn is_unknown(&self) -> bool {
         match *self {
             TypeVariableValue::Unknown { .. } => true,
@@ -197,11 +181,10 @@ impl<'tcx> TypeVariableTable<'tcx> {
     ///   The code in this module doesn't care, but it can be useful
     ///   for improving error messages.
     pub fn new_var(&mut self,
-                   universe: ty::UniverseIndex,
                    diverging: bool,
                    origin: TypeVariableOrigin)
                    -> ty::TyVid {
-        let eq_key = self.eq_relations.new_key(TypeVariableValue::Unknown { universe });
+        let eq_key = self.eq_relations.new_key(TypeVariableValue::Unknown);
 
         let sub_key = self.sub_relations.new_key(());
         assert_eq!(eq_key.vid, sub_key);
@@ -453,12 +436,8 @@ impl<'tcx> ut::UnifyValue for TypeVariableValue<'tcx> {
             (&TypeVariableValue::Known { .. }, &TypeVariableValue::Unknown { .. }) => Ok(*value1),
             (&TypeVariableValue::Unknown { .. }, &TypeVariableValue::Known { .. }) => Ok(*value2),
 
-            // If both sides are unknown, we need to pick the most restrictive universe.
-            (&TypeVariableValue::Unknown { universe: universe1 },
-             &TypeVariableValue::Unknown { universe: universe2 }) => {
-                let universe = cmp::min(universe1, universe2);
-                Ok(TypeVariableValue::Unknown { universe })
-            }
+            // If both sides are *unknown*, it hardly matters, does it?
+            (&TypeVariableValue::Unknown, &TypeVariableValue::Unknown) => Ok(*value1),
         }
     }
 }
diff --git a/src/librustc/traits/coherence.rs b/src/librustc/traits/coherence.rs
index 06926b1648df5..31f8af1f96872 100644
--- a/src/librustc/traits/coherence.rs
+++ b/src/librustc/traits/coherence.rs
@@ -92,9 +92,7 @@ fn with_fresh_ty_vars<'cx, 'gcx, 'tcx>(selcx: &mut SelectionContext<'cx, 'gcx, '
                                        -> ty::ImplHeader<'tcx>
 {
     let tcx = selcx.tcx();
-    let impl_substs = selcx.infcx().fresh_substs_for_item(param_env.universe,
-                                                          DUMMY_SP,
-                                                          impl_def_id);
+    let impl_substs = selcx.infcx().fresh_substs_for_item(DUMMY_SP, impl_def_id);
 
     let header = ty::ImplHeader {
         impl_def_id,
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
index e640cc315c44d..d2bde14732bbc 100644
--- a/src/librustc/traits/error_reporting.rs
+++ b/src/librustc/traits/error_reporting.rs
@@ -292,9 +292,7 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 
         self.tcx.for_each_relevant_impl(
             trait_ref.def_id, trait_self_ty, |def_id| {
-                let impl_substs = self.fresh_substs_for_item(param_env.universe,
-                                                             obligation.cause.span,
-                                                             def_id);
+                let impl_substs = self.fresh_substs_for_item(obligation.cause.span, def_id);
                 let impl_trait_ref = tcx
                     .impl_trait_ref(def_id)
                     .unwrap()
@@ -1285,7 +1283,6 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                            -> bool {
         struct ParamToVarFolder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
             infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
-            param_env: ty::ParamEnv<'tcx>,
             var_map: FxHashMap<Ty<'tcx>, Ty<'tcx>>
         }
 
@@ -1295,14 +1292,9 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
                 if let ty::TyParam(ty::ParamTy {name, ..}) = ty.sty {
                     let infcx = self.infcx;
-                    let param_env = self.param_env;
-                    self.var_map
-                        .entry(ty)
-                        .or_insert_with(|| {
-                            let origin = TypeVariableOrigin::TypeParameterDefinition(DUMMY_SP,
-                                                                                     name);
-                            infcx.next_ty_var(param_env.universe, origin)
-                        })
+                    self.var_map.entry(ty).or_insert_with(||
+                        infcx.next_ty_var(
+                            TypeVariableOrigin::TypeParameterDefinition(DUMMY_SP, name)))
                 } else {
                     ty.super_fold_with(self)
                 }
@@ -1314,7 +1306,6 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
 
             let cleaned_pred = pred.fold_with(&mut ParamToVarFolder {
                 infcx: self,
-                param_env,
                 var_map: FxHashMap()
             });
 
diff --git a/src/librustc/traits/mod.rs b/src/librustc/traits/mod.rs
index 1d5d3e41c9c9a..2ce1b75e3151f 100644
--- a/src/librustc/traits/mod.rs
+++ b/src/librustc/traits/mod.rs
@@ -612,8 +612,7 @@ pub fn normalize_param_env_or_error<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
            predicates);
 
     let elaborated_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
-                                           unnormalized_env.reveal,
-                                           unnormalized_env.universe);
+                                           unnormalized_env.reveal);
 
     tcx.infer_ctxt().enter(|infcx| {
         // FIXME. We should really... do something with these region
@@ -687,9 +686,7 @@ pub fn normalize_param_env_or_error<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
         debug!("normalize_param_env_or_error: resolved predicates={:?}",
                predicates);
 
-        ty::ParamEnv::new(tcx.intern_predicates(&predicates),
-                          unnormalized_env.reveal,
-                          unnormalized_env.universe)
+        ty::ParamEnv::new(tcx.intern_predicates(&predicates), unnormalized_env.reveal)
     })
 }
 
diff --git a/src/librustc/traits/project.rs b/src/librustc/traits/project.rs
index a9dc491574379..2a62d0b5ee39a 100644
--- a/src/librustc/traits/project.rs
+++ b/src/librustc/traits/project.rs
@@ -477,7 +477,6 @@ pub fn normalize_projection_type<'a, 'b, 'gcx, 'tcx>(
             let tcx = selcx.infcx().tcx;
             let def_id = projection_ty.item_def_id;
             let ty_var = selcx.infcx().next_ty_var(
-                param_env.universe,
                 TypeVariableOrigin::NormalizeProjectionType(tcx.def_span(def_id)));
             let projection = ty::Binder(ty::ProjectionPredicate {
                 projection_ty,
@@ -798,7 +797,6 @@ fn normalize_to_error<'a, 'gcx, 'tcx>(selcx: &mut SelectionContext<'a, 'gcx, 'tc
     let tcx = selcx.infcx().tcx;
     let def_id = projection_ty.item_def_id;
     let new_value = selcx.infcx().next_ty_var(
-        param_env.universe,
         TypeVariableOrigin::NormalizeProjectionType(tcx.def_span(def_id)));
     Normalized {
         value: new_value,
diff --git a/src/librustc/traits/select.rs b/src/librustc/traits/select.rs
index 11daa96134c59..93ae101eb1426 100644
--- a/src/librustc/traits/select.rs
+++ b/src/librustc/traits/select.rs
@@ -3040,8 +3040,7 @@ impl<'cx, 'gcx, 'tcx> SelectionContext<'cx, 'gcx, 'tcx> {
             snapshot);
         let skol_obligation_trait_ref = skol_obligation.trait_ref;
 
-        let impl_substs = self.infcx.fresh_substs_for_item(obligation.param_env.universe,
-                                                           obligation.cause.span,
+        let impl_substs = self.infcx.fresh_substs_for_item(obligation.cause.span,
                                                            impl_def_id);
 
         let impl_trait_ref = impl_trait_ref.subst(self.tcx(),
diff --git a/src/librustc/traits/specialize/mod.rs b/src/librustc/traits/specialize/mod.rs
index a9d1c8bcc3d99..30b2c55afa194 100644
--- a/src/librustc/traits/specialize/mod.rs
+++ b/src/librustc/traits/specialize/mod.rs
@@ -221,7 +221,7 @@ fn fulfill_implication<'a, 'gcx, 'tcx>(infcx: &InferCtxt<'a, 'gcx, 'tcx>,
                                        target_impl: DefId)
                                        -> Result<&'tcx Substs<'tcx>, ()> {
     let selcx = &mut SelectionContext::new(&infcx);
-    let target_substs = infcx.fresh_substs_for_item(param_env.universe, DUMMY_SP, target_impl);
+    let target_substs = infcx.fresh_substs_for_item(DUMMY_SP, target_impl);
     let (target_trait_ref, mut obligations) = impl_trait_ref_and_oblig(selcx,
                                                                        param_env,
                                                                        target_impl,
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index e1925d964b31e..72ba199eb2412 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -69,7 +69,7 @@ pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
 pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const};
 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
 pub use self::sty::RegionKind;
-pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid};
+pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid, SkolemizedRegionVid};
 pub use self::sty::BoundRegion::*;
 pub use self::sty::InferTy::*;
 pub use self::sty::RegionKind::*;
@@ -1344,13 +1344,15 @@ impl<'tcx> InstantiatedPredicates<'tcx> {
 /// type name in a non-zero universe is a skolemized type -- an
 /// idealized representative of "types in general" that we use for
 /// checking generic functions.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct UniverseIndex(u32);
 
 impl UniverseIndex {
     /// The root universe, where things that the user defined are
     /// visible.
-    pub const ROOT: UniverseIndex = UniverseIndex(0);
+    pub fn root() -> UniverseIndex {
+        UniverseIndex(0)
+    }
 
     /// A "subuniverse" corresponds to being inside a `forall` quantifier.
     /// So, for example, suppose we have this type in universe `U`:
@@ -1364,26 +1366,7 @@ impl UniverseIndex {
     /// region `'a`, but that region was not nameable from `U` because
     /// it was not in scope there.
     pub fn subuniverse(self) -> UniverseIndex {
-        UniverseIndex(self.0.checked_add(1).unwrap())
-    }
-
-    pub fn from(v: u32) -> UniverseIndex {
-        UniverseIndex(v)
-    }
-
-    pub fn as_u32(&self) -> u32 {
-        self.0
-    }
-
-    pub fn as_usize(&self) -> usize {
-        self.0 as usize
-    }
-
-    /// Gets the "depth" of this universe in the universe tree. This
-    /// is not really useful except for e.g. the `HashStable`
-    /// implementation
-    pub fn depth(&self) -> u32 {
-        self.0
+        UniverseIndex(self.0 + 1)
     }
 }
 
@@ -1401,17 +1384,6 @@ pub struct ParamEnv<'tcx> {
     /// want `Reveal::All` -- note that this is always paired with an
     /// empty environment. To get that, use `ParamEnv::reveal()`.
     pub reveal: traits::Reveal,
-
-    /// What is the innermost universe we have created? Starts out as
-    /// `UniverseIndex::root()` but grows from there as we enter
-    /// universal quantifiers.
-    ///
-    /// NB: At present, we exclude the universal quantifiers on the
-    /// item we are type-checking, and just consider those names as
-    /// part of the root universe. So this would only get incremented
-    /// when we enter into a higher-ranked (`for<..>`) type or trait
-    /// bound.
-    pub universe: UniverseIndex,
 }
 
 impl<'tcx> ParamEnv<'tcx> {
@@ -1420,7 +1392,7 @@ impl<'tcx> ParamEnv<'tcx> {
     /// Trait`) are left hidden, so this is suitable for ordinary
     /// type-checking.
     pub fn empty() -> Self {
-        Self::new(ty::Slice::empty(), Reveal::UserFacing, ty::UniverseIndex::ROOT)
+        Self::new(ty::Slice::empty(), Reveal::UserFacing)
     }
 
     /// Construct a trait environment with no where clauses in scope
@@ -1431,15 +1403,14 @@ impl<'tcx> ParamEnv<'tcx> {
     /// NB. If you want to have predicates in scope, use `ParamEnv::new`,
     /// or invoke `param_env.with_reveal_all()`.
     pub fn reveal_all() -> Self {
-        Self::new(ty::Slice::empty(), Reveal::All, ty::UniverseIndex::ROOT)
+        Self::new(ty::Slice::empty(), Reveal::All)
     }
 
     /// Construct a trait environment with the given set of predicates.
     pub fn new(caller_bounds: &'tcx ty::Slice<ty::Predicate<'tcx>>,
-               reveal: Reveal,
-               universe: ty::UniverseIndex)
+               reveal: Reveal)
                -> Self {
-        ty::ParamEnv { caller_bounds, reveal, universe }
+        ty::ParamEnv { caller_bounds, reveal }
     }
 
     /// Returns a new parameter environment with the same clauses, but
@@ -2731,8 +2702,7 @@ fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     // sure that this will succeed without errors anyway.
 
     let unnormalized_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates),
-                                             traits::Reveal::UserFacing,
-                                             ty::UniverseIndex::ROOT);
+                                             traits::Reveal::UserFacing);
 
     let body_id = tcx.hir.as_local_node_id(def_id).map_or(DUMMY_NODE_ID, |id| {
         tcx.hir.maybe_body_owned_by(id).map_or(id, |body| body.node_id)
diff --git a/src/librustc/ty/structural_impls.rs b/src/librustc/ty/structural_impls.rs
index 3fc20508ad7ee..8cf662ccaea92 100644
--- a/src/librustc/ty/structural_impls.rs
+++ b/src/librustc/ty/structural_impls.rs
@@ -280,7 +280,6 @@ impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
         tcx.lift(&self.caller_bounds).map(|caller_bounds| {
             ty::ParamEnv {
                 reveal: self.reveal,
-                universe: self.universe,
                 caller_bounds,
             }
         })
@@ -738,29 +737,8 @@ impl<'tcx, T:TypeFoldable<'tcx>> TypeFoldable<'tcx> for ty::Binder<T> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for ty::ParamEnv<'tcx> {
-    fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
-        ty::ParamEnv {
-            reveal: self.reveal,
-            caller_bounds: self.caller_bounds.fold_with(folder),
-            universe: self.universe.fold_with(folder),
-        }
-    }
-
-    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
-        let &ty::ParamEnv { reveal: _, ref universe, ref caller_bounds } = self;
-        universe.super_visit_with(visitor) || caller_bounds.super_visit_with(visitor)
-    }
-}
-
-impl<'tcx> TypeFoldable<'tcx> for ty::UniverseIndex {
-    fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, _folder: &mut F) -> Self {
-        *self
-    }
-
-    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, _visitor: &mut V) -> bool {
-        false
-    }
+BraceStructTypeFoldableImpl! {
+    impl<'tcx> TypeFoldable<'tcx> for ty::ParamEnv<'tcx> { reveal, caller_bounds }
 }
 
 impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Slice<ty::ExistentialPredicate<'tcx>> {
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index 2b88db503030d..ed04d41ba1457 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -1028,7 +1028,7 @@ pub enum RegionKind {
 
     /// A skolemized region - basically the higher-ranked version of ReFree.
     /// Should not exist after typeck.
-    ReSkolemized(ty::UniverseIndex, BoundRegion),
+    ReSkolemized(SkolemizedRegionVid, BoundRegion),
 
     /// Empty lifetime is for data that is never accessed.
     /// Bottom in the region lattice. We treat ReEmpty somewhat
@@ -1082,6 +1082,11 @@ newtype_index!(RegionVid
         DEBUG_FORMAT = custom,
     });
 
+#[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
+pub struct SkolemizedRegionVid {
+    pub index: u32,
+}
+
 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
 pub enum InferTy {
     TyVar(TyVid),
diff --git a/src/librustc/util/ppaux.rs b/src/librustc/util/ppaux.rs
index 056f1278c47c7..d27cda4040e56 100644
--- a/src/librustc/util/ppaux.rs
+++ b/src/librustc/util/ppaux.rs
@@ -793,7 +793,7 @@ define_print! {
                 }
 
                 ty::ReSkolemized(id, ref bound_region) => {
-                    write!(f, "ReSkolemized({:?}, {:?})", id, bound_region)
+                    write!(f, "ReSkolemized({}, {:?})", id.index, bound_region)
                 }
 
                 ty::ReEmpty => write!(f, "ReEmpty"),
diff --git a/src/librustc_driver/test.rs b/src/librustc_driver/test.rs
index 97577008377ab..9efd8844977f9 100644
--- a/src/librustc_driver/test.rs
+++ b/src/librustc_driver/test.rs
@@ -455,8 +455,7 @@ fn sub_free_bound_false_infer() {
     //! does NOT hold for any instantiation of `_#1`.
 
     test_env(EMPTY_SOURCE_STR, errors(&[]), |env| {
-        let t_infer1 = env.infcx.next_ty_var(ty::UniverseIndex::ROOT,
-                                             TypeVariableOrigin::MiscVariable(DUMMY_SP));
+        let t_infer1 = env.infcx.next_ty_var(TypeVariableOrigin::MiscVariable(DUMMY_SP));
         let t_rptr_bound1 = env.t_rptr_late_bound(1);
         env.check_not_sub(env.t_fn(&[t_infer1], env.tcx().types.isize),
                           env.t_fn(&[t_rptr_bound1], env.tcx().types.isize));
diff --git a/src/librustc_typeck/check/_match.rs b/src/librustc_typeck/check/_match.rs
index 43ff925e422f1..ae373fbad2246 100644
--- a/src/librustc_typeck/check/_match.rs
+++ b/src/librustc_typeck/check/_match.rs
@@ -296,7 +296,6 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 let element_tys_iter = (0..max_len).map(|_| self.next_ty_var(
                     // FIXME: MiscVariable for now, obtaining the span and name information
                     //       from all tuple elements isn't trivial.
-                    ty::UniverseIndex::ROOT,
                     TypeVariableOrigin::TypeInference(pat.span)));
                 let element_tys = tcx.mk_type_list(element_tys_iter);
                 let pat_ty = tcx.mk_ty(ty::TyTuple(element_tys));
@@ -307,8 +306,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 pat_ty
             }
             PatKind::Box(ref inner) => {
-                let inner_ty = self.next_ty_var(ty::UniverseIndex::ROOT,
-                                                TypeVariableOrigin::TypeInference(inner.span));
+                let inner_ty = self.next_ty_var(TypeVariableOrigin::TypeInference(inner.span));
                 let uniq_ty = tcx.mk_box(inner_ty);
 
                 if self.check_dereferencable(pat.span, expected, &inner) {
@@ -341,7 +339,6 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                         }
                         _ => {
                             let inner_ty = self.next_ty_var(
-                                ty::UniverseIndex::ROOT,
                                 TypeVariableOrigin::TypeInference(inner.span));
                             let mt = ty::TypeAndMut { ty: inner_ty, mutbl: mutbl };
                             let region = self.next_region_var(infer::PatternRegion(pat.span));
@@ -600,8 +597,7 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
             // ...but otherwise we want to use any supertype of the
             // discriminant. This is sort of a workaround, see note (*) in
             // `check_pat` for some details.
-            discrim_ty = self.next_ty_var(ty::UniverseIndex::ROOT,
-                                          TypeVariableOrigin::TypeInference(discrim.span));
+            discrim_ty = self.next_ty_var(TypeVariableOrigin::TypeInference(discrim.span));
             self.check_expr_has_type_or_error(discrim, discrim_ty);
         };
 
@@ -662,8 +658,7 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
                 // arm for inconsistent arms or to the whole match when a `()` type
                 // is required).
                 Expectation::ExpectHasType(ety) if ety != self.tcx.mk_nil() => ety,
-                _ => self.next_ty_var(ty::UniverseIndex::ROOT,
-                                      TypeVariableOrigin::MiscVariable(expr.span)),
+                _ => self.next_ty_var(TypeVariableOrigin::MiscVariable(expr.span)),
             };
             CoerceMany::with_coercion_sites(coerce_first, arms)
         };
diff --git a/src/librustc_typeck/check/closure.rs b/src/librustc_typeck/check/closure.rs
index 562c0cb1b8d0e..68b0560355fc3 100644
--- a/src/librustc_typeck/check/closure.rs
+++ b/src/librustc_typeck/check/closure.rs
@@ -110,8 +110,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             |_, _| span_bug!(expr.span, "closure has region param"),
             |_, _| {
                 self.infcx
-                    .next_ty_var(ty::UniverseIndex::ROOT,
-                                 TypeVariableOrigin::ClosureSynthetic(expr.span))
+                    .next_ty_var(TypeVariableOrigin::ClosureSynthetic(expr.span))
             },
         );
         let substs = ty::ClosureSubsts { substs };
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs
index 269ee49f38e70..bc8f107951b14 100644
--- a/src/librustc_typeck/check/coercion.rs
+++ b/src/librustc_typeck/check/coercion.rs
@@ -176,7 +176,6 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
                 // micro-optimization: no need for this if `b` is
                 // already resolved in some way.
                 let diverging_ty = self.next_diverging_ty_var(
-                    ty::UniverseIndex::ROOT,
                     TypeVariableOrigin::AdjustmentType(self.cause.span));
                 self.unify_and(&b, &diverging_ty, simple(Adjust::NeverToAny))
             } else {
@@ -510,7 +509,7 @@ impl<'f, 'gcx, 'tcx> Coerce<'f, 'gcx, 'tcx> {
         // We only have the latter, so we use an inference variable
         // for the former and let type inference do the rest.
         let origin = TypeVariableOrigin::MiscVariable(self.cause.span);
-        let coerce_target = self.next_ty_var(ty::UniverseIndex::ROOT, origin);
+        let coerce_target = self.next_ty_var(origin);
         let mut coercion = self.unify_and(coerce_target, target, |target| {
             let unsize = Adjustment {
                 kind: Adjust::Unsize,
diff --git a/src/librustc_typeck/check/compare_method.rs b/src/librustc_typeck/check/compare_method.rs
index 60ac31ac8eba8..e1e3dea9a2a11 100644
--- a/src/librustc_typeck/check/compare_method.rs
+++ b/src/librustc_typeck/check/compare_method.rs
@@ -218,8 +218,7 @@ fn compare_predicate_entailment<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     // the new hybrid bounds we computed.
     let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_node_id);
     let param_env = ty::ParamEnv::new(tcx.intern_predicates(&hybrid_preds.predicates),
-                                      Reveal::UserFacing,
-                                      ty::UniverseIndex::ROOT);
+                                      Reveal::UserFacing);
     let param_env = traits::normalize_param_env_or_error(tcx,
                                                          impl_m.def_id,
                                                          param_env,
diff --git a/src/librustc_typeck/check/dropck.rs b/src/librustc_typeck/check/dropck.rs
index d508b6df924c2..b8aa39a202bee 100644
--- a/src/librustc_typeck/check/dropck.rs
+++ b/src/librustc_typeck/check/dropck.rs
@@ -90,7 +90,7 @@ fn ensure_drop_params_and_item_params_correspond<'a, 'tcx>(
 
         let drop_impl_span = tcx.def_span(drop_impl_did);
         let fresh_impl_substs =
-            infcx.fresh_substs_for_item(ty::UniverseIndex::ROOT, drop_impl_span, drop_impl_did);
+            infcx.fresh_substs_for_item(drop_impl_span, drop_impl_did);
         let fresh_impl_self_ty = drop_impl_ty.subst(tcx, fresh_impl_substs);
 
         let cause = &ObligationCause::misc(drop_impl_span, drop_impl_node_id);
diff --git a/src/librustc_typeck/check/method/confirm.rs b/src/librustc_typeck/check/method/confirm.rs
index b777ac30920cd..a3233c8d86599 100644
--- a/src/librustc_typeck/check/method/confirm.rs
+++ b/src/librustc_typeck/check/method/confirm.rs
@@ -259,7 +259,7 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
                 // the process we will unify the transformed-self-type
                 // of the method with the actual type in order to
                 // unify some of these variables.
-                self.fresh_substs_for_item(ty::UniverseIndex::ROOT, self.span, trait_def_id)
+                self.fresh_substs_for_item(self.span, trait_def_id)
             }
 
             probe::WhereClausePick(ref poly_trait_ref) => {
@@ -336,7 +336,7 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
             {
                 self.to_ty(ast_ty)
             } else {
-                self.type_var_for_def(ty::UniverseIndex::ROOT, self.span, def)
+                self.type_var_for_def(self.span, def)
             }
         })
     }
diff --git a/src/librustc_typeck/check/method/mod.rs b/src/librustc_typeck/check/method/mod.rs
index 54f41e65d06a0..e33e4c518924e 100644
--- a/src/librustc_typeck/check/method/mod.rs
+++ b/src/librustc_typeck/check/method/mod.rs
@@ -257,7 +257,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             } else if let Some(ref input_types) = opt_input_types {
                 input_types[def.index as usize - 1]
             } else {
-                self.type_var_for_def(ty::UniverseIndex::ROOT, span, def)
+                self.type_var_for_def(span, def)
             }
         });
 
diff --git a/src/librustc_typeck/check/method/probe.rs b/src/librustc_typeck/check/method/probe.rs
index 136eb91e2abe6..fa2022e8cc994 100644
--- a/src/librustc_typeck/check/method/probe.rs
+++ b/src/librustc_typeck/check/method/probe.rs
@@ -736,9 +736,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
             Def::Method(def_id) => {
                 let fty = self.tcx.fn_sig(def_id);
                 self.probe(|_| {
-                    let substs = self.fresh_substs_for_item(ty::UniverseIndex::ROOT,
-                                                            self.span,
-                                                            method.def_id);
+                    let substs = self.fresh_substs_for_item(self.span, method.def_id);
                     let fty = fty.subst(self.tcx, substs);
                     let (fty, _) = self.replace_late_bound_regions_with_fresh_var(
                         self.span, infer::FnCall, &fty);
@@ -1389,7 +1387,7 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
                 if i < substs.len() {
                     substs.type_at(i)
                 } else {
-                    self.type_var_for_def(ty::UniverseIndex::ROOT, self.span, def)
+                    self.type_var_for_def(self.span, def)
                 }
             });
             xform_fn_sig.subst(self.tcx, substs)
@@ -1406,7 +1404,6 @@ impl<'a, 'gcx, 'tcx> ProbeContext<'a, 'gcx, 'tcx> {
                          def_id,
                          |_, _| self.tcx.types.re_erased,
                          |_, _| self.next_ty_var(
-                             ty::UniverseIndex::ROOT,
                              TypeVariableOrigin::SubstitutionPlaceholder(
                                  self.tcx.def_span(def_id))))
     }
diff --git a/src/librustc_typeck/check/method/suggest.rs b/src/librustc_typeck/check/method/suggest.rs
index 06bec8f6ff659..c4d98c8a2abb5 100644
--- a/src/librustc_typeck/check/method/suggest.rs
+++ b/src/librustc_typeck/check/method/suggest.rs
@@ -56,8 +56,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 self.autoderef(span, ty).any(|(ty, _)| {
                     self.probe(|_| {
                         let fn_once_substs = tcx.mk_substs_trait(ty,
-                            &[self.next_ty_var(ty::UniverseIndex::ROOT,
-                                               TypeVariableOrigin::MiscVariable(span))]);
+                            &[self.next_ty_var(TypeVariableOrigin::MiscVariable(span))]);
                         let trait_ref = ty::TraitRef::new(fn_once, fn_once_substs);
                         let poly_trait_ref = trait_ref.to_poly_trait_ref();
                         let obligation =
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 0f0f59c28f825..187f220f7f830 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -362,8 +362,7 @@ impl<'a, 'gcx, 'tcx> Expectation<'tcx> {
     /// hard constraint exists, creates a fresh type variable.
     fn coercion_target_type(self, fcx: &FnCtxt<'a, 'gcx, 'tcx>, span: Span) -> Ty<'tcx> {
         self.only_has_type(fcx)
-            .unwrap_or_else(|| fcx.next_ty_var(ty::UniverseIndex::ROOT,
-                                               TypeVariableOrigin::MiscVariable(span)))
+            .unwrap_or_else(|| fcx.next_ty_var(TypeVariableOrigin::MiscVariable(span)))
     }
 }
 
@@ -938,8 +937,7 @@ impl<'a, 'gcx, 'tcx> GatherLocalsVisitor<'a, 'gcx, 'tcx> {
         match ty_opt {
             None => {
                 // infer the variable's type
-                let var_ty = self.fcx.next_ty_var(ty::UniverseIndex::ROOT,
-                                                  TypeVariableOrigin::TypeInference(span));
+                let var_ty = self.fcx.next_ty_var(TypeVariableOrigin::TypeInference(span));
                 self.fcx.locals.borrow_mut().insert(nid, var_ty);
                 var_ty
             }
@@ -1052,8 +1050,7 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
     let span = body.value.span;
 
     if body.is_generator && can_be_generator.is_some() {
-        let yield_ty = fcx.next_ty_var(ty::UniverseIndex::ROOT,
-                                       TypeVariableOrigin::TypeInference(span));
+        let yield_ty = fcx.next_ty_var(TypeVariableOrigin::TypeInference(span));
         fcx.require_type_is_sized(yield_ty, span, traits::SizedYieldType);
         fcx.yield_ty = Some(yield_ty);
     }
@@ -1086,8 +1083,7 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
     // This ensures that all nested generators appear before the entry of this generator.
     // resolve_generator_interiors relies on this property.
     let gen_ty = if can_be_generator.is_some() && body.is_generator {
-        let witness = fcx.next_ty_var(ty::UniverseIndex::ROOT,
-                                      TypeVariableOrigin::MiscVariable(span));
+        let witness = fcx.next_ty_var(TypeVariableOrigin::MiscVariable(span));
         let interior = ty::GeneratorInterior {
             witness,
             movable: can_be_generator.unwrap() == hir::GeneratorMovability::Movable,
@@ -1125,7 +1121,6 @@ fn check_fn<'a, 'gcx, 'tcx>(inherited: &'a Inherited<'a, 'gcx, 'tcx>,
     let mut actual_return_ty = coercion.complete(&fcx);
     if actual_return_ty.is_never() {
         actual_return_ty = fcx.next_diverging_ty_var(
-            ty::UniverseIndex::ROOT,
             TypeVariableOrigin::DivergingFn(span));
     }
     fcx.demand_suptype(span, ret_ty, actual_return_ty);
@@ -1738,14 +1733,13 @@ impl<'a, 'gcx, 'tcx> AstConv<'gcx, 'tcx> for FnCtxt<'a, 'gcx, 'tcx> {
     }
 
     fn ty_infer(&self, span: Span) -> Ty<'tcx> {
-        self.next_ty_var(ty::UniverseIndex::ROOT,
-                         TypeVariableOrigin::TypeInference(span))
+        self.next_ty_var(TypeVariableOrigin::TypeInference(span))
     }
 
     fn ty_infer_for_def(&self,
                         ty_param_def: &ty::TypeParameterDef,
                         span: Span) -> Ty<'tcx> {
-        self.type_var_for_def(ty::UniverseIndex::ROOT, span, ty_param_def)
+        self.type_var_for_def(span, ty_param_def)
     }
 
     fn projected_ty_from_poly_trait_ref(&self,
@@ -2370,8 +2364,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             // If some lookup succeeds, write callee into table and extract index/element
             // type from the method signature.
             // If some lookup succeeded, install method in table
-            let input_ty = self.next_ty_var(ty::UniverseIndex::ROOT,
-                                            TypeVariableOrigin::AutoDeref(base_expr.span));
+            let input_ty = self.next_ty_var(TypeVariableOrigin::AutoDeref(base_expr.span));
             let method = self.try_overloaded_place_op(
                 expr.span, self_ty, &[input_ty], needs, PlaceOp::Index);
 
@@ -2810,7 +2803,6 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
             assert!(!self.tables.borrow().adjustments().contains_key(expr.hir_id),
                     "expression with never type wound up being adjusted");
             let adj_ty = self.next_diverging_ty_var(
-                ty::UniverseIndex::ROOT,
                 TypeVariableOrigin::AdjustmentType(expr.span));
             self.apply_adjustments(expr, vec![Adjustment {
                 kind: Adjust::NeverToAny,
@@ -2888,7 +2880,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         let ity = self.tcx.type_of(did);
         debug!("impl_self_ty: ity={:?}", ity);
 
-        let substs = self.fresh_substs_for_item(ty::UniverseIndex::ROOT, span, did);
+        let substs = self.fresh_substs_for_item(span, did);
         let substd_ty = self.instantiate_type_scheme(span, &substs, &ity);
 
         TypeAndSubsts { substs: substs, ty: substd_ty }
@@ -4021,8 +4013,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
 
               let element_ty = if !args.is_empty() {
                   let coerce_to = uty.unwrap_or_else(
-                      || self.next_ty_var(ty::UniverseIndex::ROOT,
-                                          TypeVariableOrigin::TypeInference(expr.span)));
+                      || self.next_ty_var(TypeVariableOrigin::TypeInference(expr.span)));
                   let mut coerce = CoerceMany::with_coercion_sites(coerce_to, args);
                   assert_eq!(self.diverges.get(), Diverges::Maybe);
                   for e in args {
@@ -4032,8 +4023,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                   }
                   coerce.complete(self)
               } else {
-                  self.next_ty_var(ty::UniverseIndex::ROOT,
-                                   TypeVariableOrigin::TypeInference(expr.span))
+                  self.next_ty_var(TypeVariableOrigin::TypeInference(expr.span))
               };
               tcx.mk_array(element_ty, args.len() as u64)
           }
@@ -4073,8 +4063,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                     (uty, uty)
                 }
                 None => {
-                    let t: Ty = self.next_ty_var(ty::UniverseIndex::ROOT,
-                                                 TypeVariableOrigin::MiscVariable(element.span));
+                    let t: Ty = self.next_ty_var(TypeVariableOrigin::MiscVariable(element.span));
                     let element_ty = self.check_expr_has_type_or_error(&element, t);
                     (element_ty, t)
                 }
@@ -4853,7 +4842,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 // Handle Self first, so we can adjust the index to match the AST.
                 if has_self && i == 0 {
                     return opt_self_ty.unwrap_or_else(|| {
-                        self.type_var_for_def(ty::UniverseIndex::ROOT, span, def)
+                        self.type_var_for_def(span, def)
                     });
                 }
                 i -= has_self as usize;
@@ -4886,7 +4875,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                 // This can also be reached in some error cases:
                 // We prefer to use inference variables instead of
                 // TyError to let type inference recover somewhat.
-                self.type_var_for_def(ty::UniverseIndex::ROOT, span, def)
+                self.type_var_for_def(span, def)
             }
         });
 
diff --git a/src/librustc_typeck/check/op.rs b/src/librustc_typeck/check/op.rs
index eae692f4cdad9..faebb370a6c46 100644
--- a/src/librustc_typeck/check/op.rs
+++ b/src/librustc_typeck/check/op.rs
@@ -174,10 +174,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         // trait matching creating lifetime constraints that are too strict.
         // E.g. adding `&'a T` and `&'b T`, given `&'x T: Add<&'x T>`, will result
         // in `&'a T <: &'x T` and `&'b T <: &'x T`, instead of `'a = 'b = 'x`.
-        let lhs_ty = self.check_expr_coercable_to_type_with_needs(
-            lhs_expr,
-            self.next_ty_var(ty::UniverseIndex::ROOT,
-                             TypeVariableOrigin::MiscVariable(lhs_expr.span)),
+        let lhs_ty = self.check_expr_coercable_to_type_with_needs(lhs_expr,
+            self.next_ty_var(TypeVariableOrigin::MiscVariable(lhs_expr.span)),
             lhs_needs);
         let lhs_ty = self.resolve_type_vars_with_obligations(lhs_ty);
 
@@ -187,8 +185,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         // using this variable as the expected type, which sometimes lets
         // us do better coercions than we would be able to do otherwise,
         // particularly for things like `String + &String`.
-        let rhs_ty_var = self.next_ty_var(ty::UniverseIndex::ROOT,
-                         TypeVariableOrigin::MiscVariable(rhs_expr.span));
+        let rhs_ty_var = self.next_ty_var(TypeVariableOrigin::MiscVariable(rhs_expr.span));
 
         let result = self.lookup_op_method(lhs_ty, &[rhs_ty_var], Op::Binary(op, is_assign));
 
diff --git a/src/librustdoc/clean/auto_trait.rs b/src/librustdoc/clean/auto_trait.rs
index 9ff3d25a45ae4..fe4f785aa915e 100644
--- a/src/librustdoc/clean/auto_trait.rs
+++ b/src/librustdoc/clean/auto_trait.rs
@@ -685,14 +685,12 @@ impl<'a, 'tcx, 'rcx> AutoTraitFinder<'a, 'tcx, 'rcx> {
             new_env = ty::ParamEnv::new(
                 tcx.mk_predicates(normalized_preds),
                 param_env.reveal,
-                ty::UniverseIndex::ROOT,
             );
         }
 
         let final_user_env = ty::ParamEnv::new(
             tcx.mk_predicates(user_computed_preds.into_iter()),
             user_env.reveal,
-            ty::UniverseIndex::ROOT,
         );
         debug!(
             "evaluate_nested_obligations(ty_did={:?}, trait_did={:?}): succeeded with '{:?}' \