diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index c3ccba487ede7..69461957f804d 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -244,7 +244,9 @@ language_item_table! {
     AsyncIterator,           sym::async_iterator,      async_iterator_trait,       Target::Trait,          GenericRequirement::Exact(0);
 
     CoroutineState,          sym::coroutine_state,     coroutine_state,            Target::Enum,           GenericRequirement::None;
-    Coroutine,               sym::coroutine,           coroutine_trait,            Target::Trait,          GenericRequirement::Minimum(1);
+    Coroutine,               sym::coroutine,           coroutine_trait,            Target::Trait,          GenericRequirement::Exact(1);
+    CoroutineReturn,         sym::coroutine_return,    coroutine_return,           Target::AssocTy,        GenericRequirement::Exact(1);
+    CoroutineYield,          sym::coroutine_yield,     coroutine_yield,            Target::AssocTy,        GenericRequirement::Exact(1);
     CoroutineResume,         sym::coroutine_resume,    coroutine_resume,           Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
 
     Unpin,                   sym::unpin,               unpin_trait,                Target::Trait,          GenericRequirement::None;
diff --git a/compiler/rustc_infer/src/infer/at.rs b/compiler/rustc_infer/src/infer/at.rs
index 01bd732a4cd84..5e9c3c64e39ed 100644
--- a/compiler/rustc_infer/src/infer/at.rs
+++ b/compiler/rustc_infer/src/infer/at.rs
@@ -225,6 +225,50 @@ impl<'a, 'tcx> At<'a, 'tcx> {
         }
     }
 
+    /// Used in the new solver since we don't care about tracking an `ObligationCause`.
+    pub fn relate_no_trace<T>(
+        self,
+        expected: T,
+        variance: ty::Variance,
+        actual: T,
+    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution>
+    where
+        T: Relate<TyCtxt<'tcx>>,
+    {
+        let mut fields = CombineFields::new(
+            self.infcx,
+            TypeTrace::dummy(self.cause),
+            self.param_env,
+            DefineOpaqueTypes::Yes,
+        );
+        fields.sub().relate_with_variance(
+            variance,
+            ty::VarianceDiagInfo::default(),
+            expected,
+            actual,
+        )?;
+        Ok(fields.goals)
+    }
+
+    /// Used in the new solver since we don't care about tracking an `ObligationCause`.
+    pub fn eq_structurally_relating_aliases_no_trace<T>(
+        self,
+        expected: T,
+        actual: T,
+    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution>
+    where
+        T: Relate<TyCtxt<'tcx>>,
+    {
+        let mut fields = CombineFields::new(
+            self.infcx,
+            TypeTrace::dummy(self.cause),
+            self.param_env,
+            DefineOpaqueTypes::Yes,
+        );
+        fields.equate(StructurallyRelateAliases::Yes).relate(expected, actual)?;
+        Ok(fields.goals)
+    }
+
     /// Computes the least-upper-bound, or mutual supertype, of two
     /// values. The order of the arguments doesn't matter, but since
     /// this can result in an error (e.g., if asked to compute LUB of
@@ -303,7 +347,7 @@ impl<'tcx> ToTrace<'tcx> for Ty<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
+            values: ValuePairs::Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
         }
     }
 }
@@ -315,7 +359,10 @@ impl<'tcx> ToTrace<'tcx> for ty::Region<'tcx> {
         a: Self,
         b: Self,
     ) -> TypeTrace<'tcx> {
-        TypeTrace { cause: cause.clone(), values: Regions(ExpectedFound::new(a_is_expected, a, b)) }
+        TypeTrace {
+            cause: cause.clone(),
+            values: ValuePairs::Regions(ExpectedFound::new(a_is_expected, a, b)),
+        }
     }
 }
 
@@ -328,7 +375,7 @@ impl<'tcx> ToTrace<'tcx> for Const<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
+            values: ValuePairs::Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
         }
     }
 }
@@ -344,13 +391,13 @@ impl<'tcx> ToTrace<'tcx> for ty::GenericArg<'tcx> {
             cause: cause.clone(),
             values: match (a.unpack(), b.unpack()) {
                 (GenericArgKind::Lifetime(a), GenericArgKind::Lifetime(b)) => {
-                    Regions(ExpectedFound::new(a_is_expected, a, b))
+                    ValuePairs::Regions(ExpectedFound::new(a_is_expected, a, b))
                 }
                 (GenericArgKind::Type(a), GenericArgKind::Type(b)) => {
-                    Terms(ExpectedFound::new(a_is_expected, a.into(), b.into()))
+                    ValuePairs::Terms(ExpectedFound::new(a_is_expected, a.into(), b.into()))
                 }
                 (GenericArgKind::Const(a), GenericArgKind::Const(b)) => {
-                    Terms(ExpectedFound::new(a_is_expected, a.into(), b.into()))
+                    ValuePairs::Terms(ExpectedFound::new(a_is_expected, a.into(), b.into()))
                 }
 
                 (
@@ -379,7 +426,10 @@ impl<'tcx> ToTrace<'tcx> for ty::Term<'tcx> {
         a: Self,
         b: Self,
     ) -> TypeTrace<'tcx> {
-        TypeTrace { cause: cause.clone(), values: Terms(ExpectedFound::new(a_is_expected, a, b)) }
+        TypeTrace {
+            cause: cause.clone(),
+            values: ValuePairs::Terms(ExpectedFound::new(a_is_expected, a, b)),
+        }
     }
 }
 
@@ -392,7 +442,7 @@ impl<'tcx> ToTrace<'tcx> for ty::TraitRef<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
+            values: ValuePairs::TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 }
@@ -406,7 +456,7 @@ impl<'tcx> ToTrace<'tcx> for ty::AliasTy<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: Aliases(ExpectedFound::new(a_is_expected, a.into(), b.into())),
+            values: ValuePairs::Aliases(ExpectedFound::new(a_is_expected, a.into(), b.into())),
         }
     }
 }
@@ -418,7 +468,10 @@ impl<'tcx> ToTrace<'tcx> for ty::AliasTerm<'tcx> {
         a: Self,
         b: Self,
     ) -> TypeTrace<'tcx> {
-        TypeTrace { cause: cause.clone(), values: Aliases(ExpectedFound::new(a_is_expected, a, b)) }
+        TypeTrace {
+            cause: cause.clone(),
+            values: ValuePairs::Aliases(ExpectedFound::new(a_is_expected, a, b)),
+        }
     }
 }
 
@@ -431,7 +484,7 @@ impl<'tcx> ToTrace<'tcx> for ty::FnSig<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: PolySigs(ExpectedFound::new(
+            values: ValuePairs::PolySigs(ExpectedFound::new(
                 a_is_expected,
                 ty::Binder::dummy(a),
                 ty::Binder::dummy(b),
@@ -449,7 +502,7 @@ impl<'tcx> ToTrace<'tcx> for ty::PolyFnSig<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: PolySigs(ExpectedFound::new(a_is_expected, a, b)),
+            values: ValuePairs::PolySigs(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 }
@@ -463,7 +516,7 @@ impl<'tcx> ToTrace<'tcx> for ty::PolyExistentialTraitRef<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: ExistentialTraitRef(ExpectedFound::new(a_is_expected, a, b)),
+            values: ValuePairs::ExistentialTraitRef(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 }
@@ -477,7 +530,7 @@ impl<'tcx> ToTrace<'tcx> for ty::PolyExistentialProjection<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: ExistentialProjection(ExpectedFound::new(a_is_expected, a, b)),
+            values: ValuePairs::ExistentialProjection(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 }
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index ed483c6cbeb41..7fb07a5d30c43 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -1707,6 +1707,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     ValuePairs::ExistentialProjection(_) => {
                         (false, Mismatch::Fixed("existential projection"))
                     }
+                    ValuePairs::Dummy => {
+                        bug!("do not expect to report a type error from a ValuePairs::Dummy")
+                    }
                 };
                 let Some(vals) = self.values_str(values) else {
                     // Derived error. Cancel the emitter.
@@ -2250,12 +2253,12 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         values: ValuePairs<'tcx>,
     ) -> Option<(DiagStyledString, DiagStyledString, Option<PathBuf>)> {
         match values {
-            infer::Regions(exp_found) => self.expected_found_str(exp_found),
-            infer::Terms(exp_found) => self.expected_found_str_term(exp_found),
-            infer::Aliases(exp_found) => self.expected_found_str(exp_found),
-            infer::ExistentialTraitRef(exp_found) => self.expected_found_str(exp_found),
-            infer::ExistentialProjection(exp_found) => self.expected_found_str(exp_found),
-            infer::TraitRefs(exp_found) => {
+            ValuePairs::Regions(exp_found) => self.expected_found_str(exp_found),
+            ValuePairs::Terms(exp_found) => self.expected_found_str_term(exp_found),
+            ValuePairs::Aliases(exp_found) => self.expected_found_str(exp_found),
+            ValuePairs::ExistentialTraitRef(exp_found) => self.expected_found_str(exp_found),
+            ValuePairs::ExistentialProjection(exp_found) => self.expected_found_str(exp_found),
+            ValuePairs::TraitRefs(exp_found) => {
                 let pretty_exp_found = ty::error::ExpectedFound {
                     expected: exp_found.expected.print_trait_sugared(),
                     found: exp_found.found.print_trait_sugared(),
@@ -2267,7 +2270,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     ret => ret,
                 }
             }
-            infer::PolySigs(exp_found) => {
+            ValuePairs::PolySigs(exp_found) => {
                 let exp_found = self.resolve_vars_if_possible(exp_found);
                 if exp_found.references_error() {
                     return None;
@@ -2275,6 +2278,9 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 let (exp, fnd) = self.cmp_fn_sig(&exp_found.expected, &exp_found.found);
                 Some((exp, fnd, None))
             }
+            ValuePairs::Dummy => {
+                bug!("do not expect to report a type error from a ValuePairs::Dummy")
+            }
         }
     }
 
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 32b50053b5076..dcf415e720fb5 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -9,9 +9,8 @@ pub use rustc_middle::ty::IntVarValue;
 pub use BoundRegionConversionTime::*;
 pub use RegionVariableOrigin::*;
 pub use SubregionOrigin::*;
-pub use ValuePairs::*;
 
-use crate::infer::relate::RelateResult;
+use crate::infer::relate::{Relate, RelateResult};
 use crate::traits::{self, ObligationCause, ObligationInspector, PredicateObligation, TraitEngine};
 use error_reporting::TypeErrCtxt;
 use free_regions::RegionRelations;
@@ -35,6 +34,7 @@ use rustc_middle::infer::unify_key::{ConstVidKey, EffectVidKey};
 use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult};
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::traits::select;
+use rustc_middle::traits::solve::{Goal, NoSolution};
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
 use rustc_middle::ty::fold::BoundVarReplacerDelegate;
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
@@ -44,7 +44,7 @@ use rustc_middle::ty::{ConstVid, EffectVid, FloatVid, IntVid, TyVid};
 use rustc_middle::ty::{GenericArg, GenericArgKind, GenericArgs, GenericArgsRef};
 use rustc_middle::{bug, span_bug};
 use rustc_span::symbol::Symbol;
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 use snapshot::undo_log::InferCtxtUndoLogs;
 use std::cell::{Cell, RefCell};
 use std::fmt;
@@ -352,27 +352,27 @@ impl<'tcx> ty::InferCtxtLike for InferCtxt<'tcx> {
         }
     }
 
-    fn universe_of_ct(&self, ct: ConstVid) -> Option<ty::UniverseIndex> {
-        // Same issue as with `universe_of_ty`
-        match self.probe_const_var(ct) {
+    fn universe_of_lt(&self, lt: ty::RegionVid) -> Option<ty::UniverseIndex> {
+        match self.inner.borrow_mut().unwrap_region_constraints().probe_value(lt) {
             Err(universe) => Some(universe),
             Ok(_) => None,
         }
     }
 
-    fn universe_of_lt(&self, lt: ty::RegionVid) -> Option<ty::UniverseIndex> {
-        match self.inner.borrow_mut().unwrap_region_constraints().probe_value(lt) {
+    fn universe_of_ct(&self, ct: ConstVid) -> Option<ty::UniverseIndex> {
+        // Same issue as with `universe_of_ty`
+        match self.probe_const_var(ct) {
             Err(universe) => Some(universe),
             Ok(_) => None,
         }
     }
 
-    fn opportunistic_resolve_lt_var(&self, vid: ty::RegionVid) -> ty::Region<'tcx> {
-        self.inner.borrow_mut().unwrap_region_constraints().opportunistic_resolve_var(self.tcx, vid)
+    fn root_ty_var(&self, var: TyVid) -> TyVid {
+        self.root_var(var)
     }
 
-    fn defining_opaque_types(&self) -> &'tcx ty::List<LocalDefId> {
-        self.defining_opaque_types
+    fn root_const_var(&self, var: ConstVid) -> ConstVid {
+        self.root_const_var(var)
     }
 
     fn opportunistic_resolve_ty_var(&self, vid: TyVid) -> Ty<'tcx> {
@@ -405,6 +405,72 @@ impl<'tcx> ty::InferCtxtLike for InferCtxt<'tcx> {
             }
         }
     }
+
+    fn opportunistic_resolve_lt_var(&self, vid: ty::RegionVid) -> ty::Region<'tcx> {
+        self.inner.borrow_mut().unwrap_region_constraints().opportunistic_resolve_var(self.tcx, vid)
+    }
+
+    fn defining_opaque_types(&self) -> &'tcx ty::List<LocalDefId> {
+        self.defining_opaque_types
+    }
+
+    fn next_ty_infer(&self) -> Ty<'tcx> {
+        self.next_ty_var(DUMMY_SP)
+    }
+
+    fn next_const_infer(&self) -> ty::Const<'tcx> {
+        self.next_const_var(DUMMY_SP)
+    }
+
+    fn fresh_args_for_item(&self, def_id: DefId) -> ty::GenericArgsRef<'tcx> {
+        self.fresh_args_for_item(DUMMY_SP, def_id)
+    }
+
+    fn instantiate_binder_with_infer<T: TypeFoldable<Self::Interner> + Copy>(
+        &self,
+        value: ty::Binder<'tcx, T>,
+    ) -> T {
+        self.instantiate_binder_with_fresh_vars(
+            DUMMY_SP,
+            BoundRegionConversionTime::HigherRankedType,
+            value,
+        )
+    }
+
+    fn enter_forall<T: TypeFoldable<TyCtxt<'tcx>> + Copy, U>(
+        &self,
+        value: ty::Binder<'tcx, T>,
+        f: impl FnOnce(T) -> U,
+    ) -> U {
+        self.enter_forall(value, f)
+    }
+
+    fn relate<T: Relate<TyCtxt<'tcx>>>(
+        &self,
+        param_env: ty::ParamEnv<'tcx>,
+        lhs: T,
+        variance: ty::Variance,
+        rhs: T,
+    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> {
+        self.at(&ObligationCause::dummy(), param_env).relate_no_trace(lhs, variance, rhs)
+    }
+
+    fn eq_structurally_relating_aliases<T: Relate<TyCtxt<'tcx>>>(
+        &self,
+        param_env: ty::ParamEnv<'tcx>,
+        lhs: T,
+        rhs: T,
+    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> {
+        self.at(&ObligationCause::dummy(), param_env)
+            .eq_structurally_relating_aliases_no_trace(lhs, rhs)
+    }
+
+    fn resolve_vars_if_possible<T>(&self, value: T) -> T
+    where
+        T: TypeFoldable<TyCtxt<'tcx>>,
+    {
+        self.resolve_vars_if_possible(value)
+    }
 }
 
 /// See the `error_reporting` module for more details.
@@ -417,6 +483,7 @@ pub enum ValuePairs<'tcx> {
     PolySigs(ExpectedFound<ty::PolyFnSig<'tcx>>),
     ExistentialTraitRef(ExpectedFound<ty::PolyExistentialTraitRef<'tcx>>),
     ExistentialProjection(ExpectedFound<ty::PolyExistentialProjection<'tcx>>),
+    Dummy,
 }
 
 impl<'tcx> ValuePairs<'tcx> {
@@ -1812,7 +1879,7 @@ impl<'tcx> TypeTrace<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
+            values: ValuePairs::Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
         }
     }
 
@@ -1824,7 +1891,7 @@ impl<'tcx> TypeTrace<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
+            values: ValuePairs::TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 
@@ -1836,9 +1903,13 @@ impl<'tcx> TypeTrace<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
+            values: ValuePairs::Terms(ExpectedFound::new(a_is_expected, a.into(), b.into())),
         }
     }
+
+    fn dummy(cause: &ObligationCause<'tcx>) -> TypeTrace<'tcx> {
+        TypeTrace { cause: cause.clone(), values: ValuePairs::Dummy }
+    }
 }
 
 impl<'tcx> SubregionOrigin<'tcx> {
diff --git a/compiler/rustc_middle/src/ty/adt.rs b/compiler/rustc_middle/src/ty/adt.rs
index 886dbd317afa3..a89ebe46c3749 100644
--- a/compiler/rustc_middle/src/ty/adt.rs
+++ b/compiler/rustc_middle/src/ty/adt.rs
@@ -204,6 +204,23 @@ impl<'tcx> rustc_type_ir::inherent::AdtDef<TyCtxt<'tcx>> for AdtDef<'tcx> {
     fn def_id(self) -> DefId {
         self.did()
     }
+
+    fn is_phantom_data(self) -> bool {
+        self.is_phantom_data()
+    }
+
+    fn all_field_tys(
+        self,
+        tcx: TyCtxt<'tcx>,
+    ) -> ty::EarlyBinder<'tcx, impl Iterator<Item = Ty<'tcx>>> {
+        ty::EarlyBinder::bind(
+            self.all_fields().map(move |field| tcx.type_of(field.did).skip_binder()),
+        )
+    }
+
+    fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> Option<ty::EarlyBinder<'tcx, Ty<'tcx>>> {
+        self.sized_constraint(tcx)
+    }
 }
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq, HashStable, TyEncodable, TyDecodable)]
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 65d744239a6ab..3651c990c9792 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -70,9 +70,9 @@ use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, Layout, LayoutS, TargetDataLayout, VariantIdx};
 use rustc_target::spec::abi;
 use rustc_type_ir::fold::TypeFoldable;
+use rustc_type_ir::lang_items::TraitSolverLangItem;
 use rustc_type_ir::TyKind::*;
-use rustc_type_ir::WithCachedTypeInfo;
-use rustc_type_ir::{CollectAndApply, Interner, TypeFlags};
+use rustc_type_ir::{CollectAndApply, Interner, TypeFlags, WithCachedTypeInfo};
 use tracing::{debug, instrument};
 
 use std::assert_matches::assert_matches;
@@ -154,7 +154,7 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
 
     type VariancesOf = &'tcx [ty::Variance];
 
-    fn variances_of(self, def_id: Self::DefId) -> Self::VariancesOf {
+    fn variances_of(self, def_id: DefId) -> Self::VariancesOf {
         self.variances_of(def_id)
     }
 
@@ -198,7 +198,7 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
 
     fn trait_ref_and_own_args_for_alias(
         self,
-        def_id: Self::DefId,
+        def_id: DefId,
         args: Self::GenericArgs,
     ) -> (rustc_type_ir::TraitRef<Self>, Self::GenericArgsSlice) {
         assert_matches!(self.def_kind(def_id), DefKind::AssocTy | DefKind::AssocConst);
@@ -246,7 +246,7 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
         self.mk_type_list_from_iter(args)
     }
 
-    fn parent(self, def_id: Self::DefId) -> Self::DefId {
+    fn parent(self, def_id: DefId) -> DefId {
         self.parent(def_id)
     }
 
@@ -259,15 +259,85 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     fn features(self) -> Self::Features {
         self.features()
     }
+
+    fn bound_coroutine_hidden_types(
+        self,
+        def_id: DefId,
+    ) -> impl IntoIterator<Item = ty::EarlyBinder<'tcx, ty::Binder<'tcx, Ty<'tcx>>>> {
+        self.bound_coroutine_hidden_types(def_id)
+    }
+
+    fn fn_sig(self, def_id: DefId) -> ty::EarlyBinder<'tcx, ty::PolyFnSig<'tcx>> {
+        self.fn_sig(def_id)
+    }
+
+    fn coroutine_movability(self, def_id: DefId) -> rustc_ast::Movability {
+        self.coroutine_movability(def_id)
+    }
+
+    fn coroutine_for_closure(self, def_id: DefId) -> DefId {
+        self.coroutine_for_closure(def_id)
+    }
+
+    fn generics_require_sized_self(self, def_id: DefId) -> bool {
+        self.generics_require_sized_self(def_id)
+    }
+
+    fn item_bounds(
+        self,
+        def_id: DefId,
+    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
+        self.item_bounds(def_id).map_bound(IntoIterator::into_iter)
+    }
+
+    fn super_predicates_of(
+        self,
+        def_id: DefId,
+    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = ty::Clause<'tcx>>> {
+        ty::EarlyBinder::bind(
+            self.super_predicates_of(def_id).instantiate_identity(self).predicates.into_iter(),
+        )
+    }
+
+    fn has_target_features(self, def_id: DefId) -> bool {
+        !self.codegen_fn_attrs(def_id).target_features.is_empty()
+    }
+
+    fn require_lang_item(self, lang_item: TraitSolverLangItem) -> DefId {
+        self.require_lang_item(
+            match lang_item {
+                TraitSolverLangItem::Future => hir::LangItem::Future,
+                TraitSolverLangItem::FutureOutput => hir::LangItem::FutureOutput,
+                TraitSolverLangItem::AsyncFnKindHelper => hir::LangItem::AsyncFnKindHelper,
+                TraitSolverLangItem::AsyncFnKindUpvars => hir::LangItem::AsyncFnKindUpvars,
+            },
+            None,
+        )
+    }
+
+    fn associated_type_def_ids(self, def_id: DefId) -> impl IntoIterator<Item = DefId> {
+        self.associated_items(def_id)
+            .in_definition_order()
+            .filter(|assoc_item| matches!(assoc_item.kind, ty::AssocKind::Type))
+            .map(|assoc_item| assoc_item.def_id)
+    }
 }
 
 impl<'tcx> rustc_type_ir::inherent::Abi<TyCtxt<'tcx>> for abi::Abi {
+    fn rust() -> Self {
+        abi::Abi::Rust
+    }
+
     fn is_rust(self) -> bool {
         matches!(self, abi::Abi::Rust)
     }
 }
 
 impl<'tcx> rustc_type_ir::inherent::Safety<TyCtxt<'tcx>> for hir::Safety {
+    fn safe() -> Self {
+        hir::Safety::Safe
+    }
+
     fn is_safe(self) -> bool {
         matches!(self, hir::Safety::Safe)
     }
@@ -281,6 +351,10 @@ impl<'tcx> rustc_type_ir::inherent::Features<TyCtxt<'tcx>> for &'tcx rustc_featu
     fn generic_const_exprs(self) -> bool {
         self.generic_const_exprs
     }
+
+    fn coroutine_clone(self) -> bool {
+        self.coroutine_clone
+    }
 }
 
 type InternedSet<'tcx, T> = ShardedHashMap<InternedInSet<'tcx, T>, ()>;
diff --git a/compiler/rustc_middle/src/ty/generic_args.rs b/compiler/rustc_middle/src/ty/generic_args.rs
index 7fff3d0132493..54c88e48614b0 100644
--- a/compiler/rustc_middle/src/ty/generic_args.rs
+++ b/compiler/rustc_middle/src/ty/generic_args.rs
@@ -41,6 +41,8 @@ pub struct GenericArg<'tcx> {
     marker: PhantomData<(Ty<'tcx>, ty::Region<'tcx>, ty::Const<'tcx>)>,
 }
 
+impl<'tcx> rustc_type_ir::inherent::GenericArg<TyCtxt<'tcx>> for GenericArg<'tcx> {}
+
 impl<'tcx> rustc_type_ir::inherent::GenericArgs<TyCtxt<'tcx>> for ty::GenericArgsRef<'tcx> {
     fn type_at(self, i: usize) -> Ty<'tcx> {
         self.type_at(i)
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 83f8de6b6f93f..c322c87bce4ad 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -488,6 +488,8 @@ pub struct Term<'tcx> {
     marker: PhantomData<(Ty<'tcx>, Const<'tcx>)>,
 }
 
+impl<'tcx> rustc_type_ir::inherent::Term<TyCtxt<'tcx>> for Term<'tcx> {}
+
 impl<'tcx> rustc_type_ir::inherent::IntoKind for Term<'tcx> {
     type Kind = TermKind<'tcx>;
 
diff --git a/compiler/rustc_middle/src/ty/predicate.rs b/compiler/rustc_middle/src/ty/predicate.rs
index 785aa8d456fc6..ae36f2624ca5f 100644
--- a/compiler/rustc_middle/src/ty/predicate.rs
+++ b/compiler/rustc_middle/src/ty/predicate.rs
@@ -49,6 +49,18 @@ impl<'tcx> rustc_type_ir::inherent::Predicate<TyCtxt<'tcx>> for Predicate<'tcx>
     fn is_coinductive(self, interner: TyCtxt<'tcx>) -> bool {
         self.is_coinductive(interner)
     }
+
+    fn allow_normalization(self) -> bool {
+        self.allow_normalization()
+    }
+}
+
+impl<'tcx> rustc_type_ir::inherent::IntoKind for Predicate<'tcx> {
+    type Kind = ty::Binder<'tcx, ty::PredicateKind<'tcx>>;
+
+    fn kind(self) -> Self::Kind {
+        self.kind()
+    }
 }
 
 impl<'tcx> rustc_type_ir::visit::Flags for Predicate<'tcx> {
@@ -120,6 +132,7 @@ impl<'tcx> Predicate<'tcx> {
     /// unsoundly accept some programs. See #91068.
     #[inline]
     pub fn allow_normalization(self) -> bool {
+        // Keep this in sync with the one in `rustc_type_ir::inherent`!
         match self.kind().skip_binder() {
             PredicateKind::Clause(ClauseKind::WellFormed(_))
             | PredicateKind::AliasRelate(..)
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index ba9ed0d5b70a6..8308e537e5edf 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -786,6 +786,10 @@ impl<'tcx> rustc_type_ir::inherent::Ty<TyCtxt<'tcx>> for Ty<'tcx> {
         tcx.types.bool
     }
 
+    fn new_u8(tcx: TyCtxt<'tcx>) -> Self {
+        tcx.types.u8
+    }
+
     fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferTy) -> Self {
         Ty::new_infer(tcx, infer)
     }
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index e245dfb9f5d77..c89323b7f1691 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -635,7 +635,9 @@ symbols! {
         coroutine,
         coroutine_clone,
         coroutine_resume,
+        coroutine_return,
         coroutine_state,
+        coroutine_yield,
         coroutines,
         cosf128,
         cosf16,
diff --git a/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
index 98f98d9992d30..d6074617cafe7 100644
--- a/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
+++ b/compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
@@ -1,14 +1,14 @@
 //! Code which is used by built-in goals that match "structurally", such a auto
 //! traits, `Copy`/`Clone`.
+
+use rustc_ast_ir::{Movability, Mutability};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_hir::LangItem;
-use rustc_hir::{def_id::DefId, Movability, Mutability};
-use rustc_infer::infer::InferCtxt;
-use rustc_infer::traits::query::NoSolution;
-use rustc_macros::{TypeFoldable, TypeVisitable};
-use rustc_middle::bug;
-use rustc_middle::traits::solve::Goal;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, Upcast};
+use rustc_next_trait_solver::solve::{Goal, NoSolution};
+use rustc_type_ir::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
+use rustc_type_ir::inherent::*;
+use rustc_type_ir::lang_items::TraitSolverLangItem;
+use rustc_type_ir::{self as ty, InferCtxtLike, Interner, Upcast};
+use rustc_type_ir_macros::{TypeFoldable_Generic, TypeVisitable_Generic};
 
 use crate::solve::EvalCtxt;
 
@@ -17,12 +17,16 @@ use crate::solve::EvalCtxt;
 // For types with an "existential" binder, i.e. coroutine witnesses, we also
 // instantiate the binder with placeholders eagerly.
 #[instrument(level = "trace", skip(ecx), ret)]
-pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
-    ecx: &EvalCtxt<'_, InferCtxt<'tcx>>,
-    ty: Ty<'tcx>,
-) -> Result<Vec<ty::Binder<'tcx, Ty<'tcx>>>, NoSolution> {
+pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<Infcx, I>(
+    ecx: &EvalCtxt<'_, Infcx>,
+    ty: I::Ty,
+) -> Result<Vec<ty::Binder<I, I::Ty>>, NoSolution>
+where
+    Infcx: InferCtxtLike<Interner = I>,
+    I: Interner,
+{
     let tcx = ecx.interner();
-    match *ty.kind() {
+    match ty.kind() {
         ty::Uint(_)
         | ty::Int(_)
         | ty::Bool
@@ -34,7 +38,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
         | ty::Char => Ok(vec![]),
 
         // Treat `str` like it's defined as `struct str([u8]);`
-        ty::Str => Ok(vec![ty::Binder::dummy(Ty::new_slice(tcx, tcx.types.u8))]),
+        ty::Str => Ok(vec![ty::Binder::dummy(Ty::new_slice(tcx, Ty::new_u8(tcx)))]),
 
         ty::Dynamic(..)
         | ty::Param(..)
@@ -43,7 +47,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
         | ty::Placeholder(..)
         | ty::Bound(..)
         | ty::Infer(_) => {
-            bug!("unexpected type `{ty}`")
+            panic!("unexpected type `{ty:?}`")
         }
 
         ty::RawPtr(element_ty, _) | ty::Ref(_, element_ty, _) => {
@@ -56,7 +60,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
 
         ty::Tuple(tys) => {
             // (T1, ..., Tn) -- meets any bound that all of T1...Tn meet
-            Ok(tys.iter().map(ty::Binder::dummy).collect())
+            Ok(tys.into_iter().map(ty::Binder::dummy).collect())
         }
 
         ty::Closure(_, args) => Ok(vec![ty::Binder::dummy(args.as_closure().tupled_upvars_ty())]),
@@ -76,31 +80,38 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_auto_trait<'tcx>(
         ty::CoroutineWitness(def_id, args) => Ok(ecx
             .interner()
             .bound_coroutine_hidden_types(def_id)
-            .map(|bty| bty.instantiate(tcx, args))
+            .into_iter()
+            .map(|bty| bty.instantiate(tcx, &args))
             .collect()),
 
         // For `PhantomData<T>`, we pass `T`.
         ty::Adt(def, args) if def.is_phantom_data() => Ok(vec![ty::Binder::dummy(args.type_at(0))]),
 
-        ty::Adt(def, args) => {
-            Ok(def.all_fields().map(|f| ty::Binder::dummy(f.ty(tcx, args))).collect())
-        }
+        ty::Adt(def, args) => Ok(def
+            .all_field_tys(tcx)
+            .iter_instantiated(tcx, &args)
+            .map(ty::Binder::dummy)
+            .collect()),
 
         ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
             // We can resolve the `impl Trait` to its concrete type,
             // which enforces a DAG between the functions requiring
             // the auto trait bounds in question.
-            Ok(vec![ty::Binder::dummy(tcx.type_of(def_id).instantiate(tcx, args))])
+            Ok(vec![ty::Binder::dummy(tcx.type_of(def_id).instantiate(tcx, &args))])
         }
     }
 }
 
 #[instrument(level = "trace", skip(ecx), ret)]
-pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
-    ecx: &EvalCtxt<'_, InferCtxt<'tcx>>,
-    ty: Ty<'tcx>,
-) -> Result<Vec<ty::Binder<'tcx, Ty<'tcx>>>, NoSolution> {
-    match *ty.kind() {
+pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<Infcx, I>(
+    ecx: &EvalCtxt<'_, Infcx>,
+    ty: I::Ty,
+) -> Result<Vec<ty::Binder<I, I::Ty>>, NoSolution>
+where
+    Infcx: InferCtxtLike<Interner = I>,
+    I: Interner,
+{
+    match ty.kind() {
         // impl Sized for u*, i*, bool, f*, FnDef, FnPtr, *(const/mut) T, char, &mut? T, [T; N], dyn* Trait, !
         // impl Sized for Coroutine, CoroutineWitness, Closure, CoroutineClosure
         ty::Infer(ty::IntVar(_) | ty::FloatVar(_))
@@ -133,7 +144,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
 
         ty::Bound(..)
         | ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
-            bug!("unexpected type `{ty}`")
+            panic!("unexpected type `{ty:?}`")
         }
 
         // impl Sized for ()
@@ -151,7 +162,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
         //   if the ADT is sized for all possible args.
         ty::Adt(def, args) => {
             if let Some(sized_crit) = def.sized_constraint(ecx.interner()) {
-                Ok(vec![ty::Binder::dummy(sized_crit.instantiate(ecx.interner(), args))])
+                Ok(vec![ty::Binder::dummy(sized_crit.instantiate(ecx.interner(), &args))])
             } else {
                 Ok(vec![])
             }
@@ -160,11 +171,15 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
 }
 
 #[instrument(level = "trace", skip(ecx), ret)]
-pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
-    ecx: &EvalCtxt<'_, InferCtxt<'tcx>>,
-    ty: Ty<'tcx>,
-) -> Result<Vec<ty::Binder<'tcx, Ty<'tcx>>>, NoSolution> {
-    match *ty.kind() {
+pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<Infcx, I>(
+    ecx: &EvalCtxt<'_, Infcx>,
+    ty: I::Ty,
+) -> Result<Vec<ty::Binder<I, I::Ty>>, NoSolution>
+where
+    Infcx: InferCtxtLike<Interner = I>,
+    I: Interner,
+{
+    match ty.kind() {
         // impl Copy/Clone for FnDef, FnPtr
         ty::FnDef(..) | ty::FnPtr(_) | ty::Error(_) => Ok(vec![]),
 
@@ -196,11 +211,11 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
 
         ty::Bound(..)
         | ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
-            bug!("unexpected type `{ty}`")
+            panic!("unexpected type `{ty:?}`")
         }
 
         // impl Copy/Clone for (T1, T2, .., Tn) where T1: Copy/Clone, T2: Copy/Clone, .. Tn: Copy/Clone
-        ty::Tuple(tys) => Ok(tys.iter().map(ty::Binder::dummy).collect()),
+        ty::Tuple(tys) => Ok(tys.into_iter().map(ty::Binder::dummy).collect()),
 
         // impl Copy/Clone for Closure where Self::TupledUpvars: Copy/Clone
         ty::Closure(_, args) => Ok(vec![ty::Binder::dummy(args.as_closure().tupled_upvars_ty())]),
@@ -212,7 +227,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
         ty::Coroutine(def_id, args) => match ecx.interner().coroutine_movability(def_id) {
             Movability::Static => Err(NoSolution),
             Movability::Movable => {
-                if ecx.interner().features().coroutine_clone {
+                if ecx.interner().features().coroutine_clone() {
                     let coroutine = args.as_coroutine();
                     Ok(vec![
                         ty::Binder::dummy(coroutine.tupled_upvars_ty()),
@@ -228,27 +243,26 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_copy_clone_trait<'tcx>(
         ty::CoroutineWitness(def_id, args) => Ok(ecx
             .interner()
             .bound_coroutine_hidden_types(def_id)
-            .map(|bty| bty.instantiate(ecx.interner(), args))
+            .into_iter()
+            .map(|bty| bty.instantiate(ecx.interner(), &args))
             .collect()),
     }
 }
 
 // Returns a binder of the tupled inputs types and output type from a builtin callable type.
-pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    self_ty: Ty<'tcx>,
+pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<I: Interner>(
+    tcx: I,
+    self_ty: I::Ty,
     goal_kind: ty::ClosureKind,
-) -> Result<Option<ty::Binder<'tcx, (Ty<'tcx>, Ty<'tcx>)>>, NoSolution> {
-    match *self_ty.kind() {
+) -> Result<Option<ty::Binder<I, (I::Ty, I::Ty)>>, NoSolution> {
+    match self_ty.kind() {
         // keep this in sync with assemble_fn_pointer_candidates until the old solver is removed.
         ty::FnDef(def_id, args) => {
             let sig = tcx.fn_sig(def_id);
-            if sig.skip_binder().is_fn_trait_compatible()
-                && tcx.codegen_fn_attrs(def_id).target_features.is_empty()
-            {
+            if sig.skip_binder().is_fn_trait_compatible() && !tcx.has_target_features(def_id) {
                 Ok(Some(
-                    sig.instantiate(tcx, args)
-                        .map_bound(|sig| (Ty::new_tup(tcx, sig.inputs()), sig.output())),
+                    sig.instantiate(tcx, &args)
+                        .map_bound(|sig| (Ty::new_tup(tcx, &sig.inputs()), sig.output())),
                 ))
             } else {
                 Err(NoSolution)
@@ -257,7 +271,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
         // keep this in sync with assemble_fn_pointer_candidates until the old solver is removed.
         ty::FnPtr(sig) => {
             if sig.is_fn_trait_compatible() {
-                Ok(Some(sig.map_bound(|sig| (Ty::new_tup(tcx, sig.inputs()), sig.output()))))
+                Ok(Some(sig.map_bound(|sig| (Ty::new_tup(tcx, &sig.inputs()), sig.output()))))
             } else {
                 Err(NoSolution)
             }
@@ -311,7 +325,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
                     tcx,
                     goal_kind,
                     // No captures by ref, so this doesn't matter.
-                    tcx.lifetimes.re_static,
+                    Region::new_static(tcx),
                     def_id,
                     args,
                     sig,
@@ -326,7 +340,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
                 coroutine_closure_to_ambiguous_coroutine(
                     tcx,
                     goal_kind, // No captures by ref, so this doesn't matter.
-                    tcx.lifetimes.re_static,
+                    Region::new_static(tcx),
                     def_id,
                     args,
                     sig,
@@ -362,22 +376,24 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<'tcx>(
 
         ty::Bound(..)
         | ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
-            bug!("unexpected type `{self_ty}`")
+            panic!("unexpected type `{self_ty:?}`")
         }
     }
 }
 
 /// Relevant types for an async callable, including its inputs, output,
 /// and the return type you get from awaiting the output.
-#[derive(Copy, Clone, Debug, TypeVisitable, TypeFoldable)]
-pub(in crate::solve) struct AsyncCallableRelevantTypes<'tcx> {
-    pub tupled_inputs_ty: Ty<'tcx>,
+#[derive(derivative::Derivative)]
+#[derivative(Clone(bound = ""), Copy(bound = ""), Debug(bound = ""))]
+#[derive(TypeVisitable_Generic, TypeFoldable_Generic)]
+pub(in crate::solve) struct AsyncCallableRelevantTypes<I: Interner> {
+    pub tupled_inputs_ty: I::Ty,
     /// Type returned by calling the closure
     /// i.e. `f()`.
-    pub output_coroutine_ty: Ty<'tcx>,
+    pub output_coroutine_ty: I::Ty,
     /// Type returned by `await`ing the output
     /// i.e. `f().await`.
-    pub coroutine_return_ty: Ty<'tcx>,
+    pub coroutine_return_ty: I::Ty,
 }
 
 // Returns a binder of the tupled inputs types, output type, and coroutine type
@@ -385,16 +401,13 @@ pub(in crate::solve) struct AsyncCallableRelevantTypes<'tcx> {
 // the coroutine-closure, emit an additional trait predicate for `AsyncFnKindHelper`
 // which enforces the closure is actually callable with the given trait. When we
 // know the kind already, we can short-circuit this check.
-pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    self_ty: Ty<'tcx>,
+pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<I: Interner>(
+    tcx: I,
+    self_ty: I::Ty,
     goal_kind: ty::ClosureKind,
-    env_region: ty::Region<'tcx>,
-) -> Result<
-    (ty::Binder<'tcx, AsyncCallableRelevantTypes<'tcx>>, Vec<ty::Predicate<'tcx>>),
-    NoSolution,
-> {
-    match *self_ty.kind() {
+    env_region: I::Region,
+) -> Result<(ty::Binder<I, AsyncCallableRelevantTypes<I>>, Vec<I::Predicate>), NoSolution> {
+    match self_ty.kind() {
         ty::CoroutineClosure(def_id, args) => {
             let args = args.as_coroutine_closure();
             let kind_ty = args.kind_ty();
@@ -421,7 +434,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
                 nested.push(
                     ty::TraitRef::new(
                         tcx,
-                        tcx.require_lang_item(LangItem::AsyncFnKindHelper, None),
+                        tcx.require_lang_item(TraitSolverLangItem::AsyncFnKindHelper),
                         [kind_ty, Ty::from_closure_kind(tcx, goal_kind)],
                     )
                     .upcast(tcx),
@@ -445,7 +458,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
         ty::FnDef(..) | ty::FnPtr(..) => {
             let bound_sig = self_ty.fn_sig(tcx);
             let sig = bound_sig.skip_binder();
-            let future_trait_def_id = tcx.require_lang_item(LangItem::Future, None);
+            let future_trait_def_id = tcx.require_lang_item(TraitSolverLangItem::Future);
             // `FnDef` and `FnPtr` only implement `AsyncFn*` when their
             // return type implements `Future`.
             let nested = vec![
@@ -453,11 +466,11 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
                     .rebind(ty::TraitRef::new(tcx, future_trait_def_id, [sig.output()]))
                     .upcast(tcx),
             ];
-            let future_output_def_id = tcx.require_lang_item(LangItem::FutureOutput, None);
+            let future_output_def_id = tcx.require_lang_item(TraitSolverLangItem::FutureOutput);
             let future_output_ty = Ty::new_projection(tcx, future_output_def_id, [sig.output()]);
             Ok((
                 bound_sig.rebind(AsyncCallableRelevantTypes {
-                    tupled_inputs_ty: Ty::new_tup(tcx, sig.inputs()),
+                    tupled_inputs_ty: Ty::new_tup(tcx, &sig.inputs()),
                     output_coroutine_ty: sig.output(),
                     coroutine_return_ty: future_output_ty,
                 }),
@@ -468,7 +481,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
             let args = args.as_closure();
             let bound_sig = args.sig();
             let sig = bound_sig.skip_binder();
-            let future_trait_def_id = tcx.require_lang_item(LangItem::Future, None);
+            let future_trait_def_id = tcx.require_lang_item(TraitSolverLangItem::Future);
             // `Closure`s only implement `AsyncFn*` when their return type
             // implements `Future`.
             let mut nested = vec![
@@ -486,7 +499,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
                 }
             } else {
                 let async_fn_kind_trait_def_id =
-                    tcx.require_lang_item(LangItem::AsyncFnKindHelper, None);
+                    tcx.require_lang_item(TraitSolverLangItem::AsyncFnKindHelper);
                 // When we don't know the closure kind (and therefore also the closure's upvars,
                 // which are computed at the same time), we must delay the computation of the
                 // generator's upvars. We do this using the `AsyncFnKindHelper`, which as a trait
@@ -504,7 +517,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
                 );
             }
 
-            let future_output_def_id = tcx.require_lang_item(LangItem::FutureOutput, None);
+            let future_output_def_id = tcx.require_lang_item(TraitSolverLangItem::FutureOutput);
             let future_output_ty = Ty::new_projection(tcx, future_output_def_id, [sig.output()]);
             Ok((
                 bound_sig.rebind(AsyncCallableRelevantTypes {
@@ -542,21 +555,21 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
 
         ty::Bound(..)
         | ty::Infer(ty::TyVar(_) | ty::FreshTy(_) | ty::FreshIntTy(_) | ty::FreshFloatTy(_)) => {
-            bug!("unexpected type `{self_ty}`")
+            panic!("unexpected type `{self_ty:?}`")
         }
     }
 }
 
 /// Given a coroutine-closure, project to its returned coroutine when we are *certain*
 /// that the closure's kind is compatible with the goal.
-fn coroutine_closure_to_certain_coroutine<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn coroutine_closure_to_certain_coroutine<I: Interner>(
+    tcx: I,
     goal_kind: ty::ClosureKind,
-    goal_region: ty::Region<'tcx>,
-    def_id: DefId,
-    args: ty::CoroutineClosureArgs<TyCtxt<'tcx>>,
-    sig: ty::CoroutineClosureSignature<TyCtxt<'tcx>>,
-) -> Ty<'tcx> {
+    goal_region: I::Region,
+    def_id: I::DefId,
+    args: ty::CoroutineClosureArgs<I>,
+    sig: ty::CoroutineClosureSignature<I>,
+) -> I::Ty {
     sig.to_coroutine_given_kind_and_upvars(
         tcx,
         args.parent_args(),
@@ -573,20 +586,20 @@ fn coroutine_closure_to_certain_coroutine<'tcx>(
 /// yet what the closure's upvars are.
 ///
 /// Note that we do not also push a `AsyncFnKindHelper` goal here.
-fn coroutine_closure_to_ambiguous_coroutine<'tcx>(
-    tcx: TyCtxt<'tcx>,
+fn coroutine_closure_to_ambiguous_coroutine<I: Interner>(
+    tcx: I,
     goal_kind: ty::ClosureKind,
-    goal_region: ty::Region<'tcx>,
-    def_id: DefId,
-    args: ty::CoroutineClosureArgs<TyCtxt<'tcx>>,
-    sig: ty::CoroutineClosureSignature<TyCtxt<'tcx>>,
-) -> Ty<'tcx> {
-    let upvars_projection_def_id = tcx.require_lang_item(LangItem::AsyncFnKindUpvars, None);
+    goal_region: I::Region,
+    def_id: I::DefId,
+    args: ty::CoroutineClosureArgs<I>,
+    sig: ty::CoroutineClosureSignature<I>,
+) -> I::Ty {
+    let upvars_projection_def_id = tcx.require_lang_item(TraitSolverLangItem::AsyncFnKindUpvars);
     let tupled_upvars_ty = Ty::new_projection(
         tcx,
         upvars_projection_def_id,
         [
-            ty::GenericArg::from(args.kind_ty()),
+            I::GenericArg::from(args.kind_ty()),
             Ty::from_closure_kind(tcx, goal_kind).into(),
             goal_region.into(),
             sig.tupled_inputs_ty.into(),
@@ -643,41 +656,44 @@ fn coroutine_closure_to_ambiguous_coroutine<'tcx>(
 // This is unsound in general and once that is fixed, we don't need to
 // normalize eagerly here. See https://github.com/lcnr/solver-woes/issues/9
 // for more details.
-pub(in crate::solve) fn predicates_for_object_candidate<'tcx>(
-    ecx: &EvalCtxt<'_, InferCtxt<'tcx>>,
-    param_env: ty::ParamEnv<'tcx>,
-    trait_ref: ty::TraitRef<'tcx>,
-    object_bound: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
-) -> Vec<Goal<'tcx, ty::Predicate<'tcx>>> {
+pub(in crate::solve) fn predicates_for_object_candidate<Infcx, I>(
+    ecx: &EvalCtxt<'_, Infcx>,
+    param_env: I::ParamEnv,
+    trait_ref: ty::TraitRef<I>,
+    object_bounds: I::BoundExistentialPredicates,
+) -> Vec<Goal<I, I::Predicate>>
+where
+    Infcx: InferCtxtLike<Interner = I>,
+    I: Interner,
+{
     let tcx = ecx.interner();
     let mut requirements = vec![];
-    requirements.extend(
-        tcx.super_predicates_of(trait_ref.def_id).instantiate(tcx, trait_ref.args).predicates,
-    );
-    for item in tcx.associated_items(trait_ref.def_id).in_definition_order() {
-        // FIXME(associated_const_equality): Also add associated consts to
-        // the requirements here.
-        if item.kind == ty::AssocKind::Type {
-            // associated types that require `Self: Sized` do not show up in the built-in
-            // implementation of `Trait for dyn Trait`, and can be dropped here.
-            if tcx.generics_require_sized_self(item.def_id) {
-                continue;
-            }
-
-            requirements
-                .extend(tcx.item_bounds(item.def_id).iter_instantiated(tcx, trait_ref.args));
+    requirements
+        .extend(tcx.super_predicates_of(trait_ref.def_id).iter_instantiated(tcx, &trait_ref.args));
+
+    // FIXME(associated_const_equality): Also add associated consts to
+    // the requirements here.
+    for associated_type_def_id in tcx.associated_type_def_ids(trait_ref.def_id) {
+        // associated types that require `Self: Sized` do not show up in the built-in
+        // implementation of `Trait for dyn Trait`, and can be dropped here.
+        if tcx.generics_require_sized_self(associated_type_def_id) {
+            continue;
         }
+
+        requirements.extend(
+            tcx.item_bounds(associated_type_def_id).iter_instantiated(tcx, &trait_ref.args),
+        );
     }
 
     let mut replace_projection_with = FxHashMap::default();
-    for bound in object_bound {
+    for bound in object_bounds {
         if let ty::ExistentialPredicate::Projection(proj) = bound.skip_binder() {
             let proj = proj.with_self_ty(tcx, trait_ref.self_ty());
             let old_ty = replace_projection_with.insert(proj.def_id(), bound.rebind(proj));
             assert_eq!(
                 old_ty,
                 None,
-                "{} has two generic parameters: {} and {}",
+                "{:?} has two generic parameters: {:?} and {:?}",
                 proj.projection_term,
                 proj.term,
                 old_ty.unwrap()
@@ -696,20 +712,22 @@ pub(in crate::solve) fn predicates_for_object_candidate<'tcx>(
         .collect()
 }
 
-struct ReplaceProjectionWith<'a, 'tcx> {
-    ecx: &'a EvalCtxt<'a, InferCtxt<'tcx>>,
-    param_env: ty::ParamEnv<'tcx>,
-    mapping: FxHashMap<DefId, ty::PolyProjectionPredicate<'tcx>>,
-    nested: Vec<Goal<'tcx, ty::Predicate<'tcx>>>,
+struct ReplaceProjectionWith<'a, Infcx: InferCtxtLike<Interner = I>, I: Interner> {
+    ecx: &'a EvalCtxt<'a, Infcx>,
+    param_env: I::ParamEnv,
+    mapping: FxHashMap<I::DefId, ty::Binder<I, ty::ProjectionPredicate<I>>>,
+    nested: Vec<Goal<I, I::Predicate>>,
 }
 
-impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReplaceProjectionWith<'_, 'tcx> {
-    fn interner(&self) -> TyCtxt<'tcx> {
+impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeFolder<I>
+    for ReplaceProjectionWith<'_, Infcx, I>
+{
+    fn interner(&self) -> I {
         self.ecx.interner()
     }
 
-    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        if let ty::Alias(ty::Projection, alias_ty) = *ty.kind()
+    fn fold_ty(&mut self, ty: I::Ty) -> I::Ty {
+        if let ty::Alias(ty::Projection, alias_ty) = ty.kind()
             && let Some(replacement) = self.mapping.get(&alias_ty.def_id)
         {
             // We may have a case where our object type's projection bound is higher-ranked,
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
index 43013a01069e5..860c580374d13 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
@@ -1,9 +1,6 @@
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir::def_id::DefId;
-use rustc_infer::infer::at::ToTrace;
-use rustc_infer::infer::{
-    BoundRegionConversionTime, DefineOpaqueTypes, InferCtxt, InferOk, TyCtxtInferExt,
-};
+use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::query::NoSolution;
 use rustc_infer::traits::solve::{MaybeCause, NestedNormalizationGoals};
 use rustc_infer::traits::ObligationCause;
@@ -15,11 +12,13 @@ use rustc_middle::traits::solve::{
 use rustc_middle::ty::AliasRelationDirection;
 use rustc_middle::ty::TypeFolder;
 use rustc_middle::ty::{
-    self, InferCtxtLike, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable,
-    TypeVisitable, TypeVisitableExt, TypeVisitor,
+    self, InferCtxtLike, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable, TypeVisitableExt,
 };
 use rustc_span::DUMMY_SP;
 use rustc_type_ir::fold::TypeSuperFoldable;
+use rustc_type_ir::inherent::*;
+use rustc_type_ir::relate::Relate;
+use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use rustc_type_ir::{self as ir, CanonicalVarValues, Interner};
 use rustc_type_ir_macros::{Lift_Generic, TypeFoldable_Generic, TypeVisitable_Generic};
 use std::ops::ControlFlow;
@@ -456,28 +455,6 @@ impl<'a, 'tcx> EvalCtxt<'a, InferCtxt<'tcx>> {
         }
     }
 
-    #[instrument(level = "trace", skip(self))]
-    pub(super) fn add_normalizes_to_goal(&mut self, mut goal: Goal<'tcx, ty::NormalizesTo<'tcx>>) {
-        goal.predicate = goal
-            .predicate
-            .fold_with(&mut ReplaceAliasWithInfer { ecx: self, param_env: goal.param_env });
-        self.inspect.add_normalizes_to_goal(self.infcx, self.max_input_universe, goal);
-        self.nested_goals.normalizes_to_goals.push(goal);
-    }
-
-    #[instrument(level = "debug", skip(self))]
-    pub(super) fn add_goal(
-        &mut self,
-        source: GoalSource,
-        mut goal: Goal<'tcx, ty::Predicate<'tcx>>,
-    ) {
-        goal.predicate = goal
-            .predicate
-            .fold_with(&mut ReplaceAliasWithInfer { ecx: self, param_env: goal.param_env });
-        self.inspect.add_goal(self.infcx, self.max_input_universe, source, goal);
-        self.nested_goals.goals.push((source, goal));
-    }
-
     // Recursively evaluates all the goals added to this `EvalCtxt` to completion, returning
     // the certainty of all the goals.
     #[instrument(level = "trace", skip(self))]
@@ -600,27 +577,61 @@ impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> EvalCtxt<'_, Infcx> {
     pub(super) fn interner(&self) -> I {
         self.infcx.interner()
     }
-}
 
-impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
-    pub(super) fn next_ty_infer(&mut self) -> Ty<'tcx> {
-        let ty = self.infcx.next_ty_var(DUMMY_SP);
+    #[instrument(level = "trace", skip(self))]
+    pub(super) fn add_normalizes_to_goal(
+        &mut self,
+        mut goal: ir::solve::Goal<I, ir::NormalizesTo<I>>,
+    ) {
+        goal.predicate = goal
+            .predicate
+            .fold_with(&mut ReplaceAliasWithInfer { ecx: self, param_env: goal.param_env });
+        self.inspect.add_normalizes_to_goal(self.infcx, self.max_input_universe, goal);
+        self.nested_goals.normalizes_to_goals.push(goal);
+    }
+
+    #[instrument(level = "debug", skip(self))]
+    pub(super) fn add_goal(
+        &mut self,
+        source: GoalSource,
+        mut goal: ir::solve::Goal<I, I::Predicate>,
+    ) {
+        goal.predicate = goal
+            .predicate
+            .fold_with(&mut ReplaceAliasWithInfer { ecx: self, param_env: goal.param_env });
+        self.inspect.add_goal(self.infcx, self.max_input_universe, source, goal);
+        self.nested_goals.goals.push((source, goal));
+    }
+
+    #[instrument(level = "trace", skip(self, goals))]
+    pub(super) fn add_goals(
+        &mut self,
+        source: GoalSource,
+        goals: impl IntoIterator<Item = ir::solve::Goal<I, I::Predicate>>,
+    ) {
+        for goal in goals {
+            self.add_goal(source, goal);
+        }
+    }
+
+    pub(super) fn next_ty_infer(&mut self) -> I::Ty {
+        let ty = self.infcx.next_ty_infer();
         self.inspect.add_var_value(ty);
         ty
     }
 
-    pub(super) fn next_const_infer(&mut self) -> ty::Const<'tcx> {
-        let ct = self.infcx.next_const_var(DUMMY_SP);
+    pub(super) fn next_const_infer(&mut self) -> I::Const {
+        let ct = self.infcx.next_const_infer();
         self.inspect.add_var_value(ct);
         ct
     }
 
     /// Returns a ty infer or a const infer depending on whether `kind` is a `Ty` or `Const`.
     /// If `kind` is an integer inference variable this will still return a ty infer var.
-    pub(super) fn next_term_infer_of_kind(&mut self, kind: ty::Term<'tcx>) -> ty::Term<'tcx> {
-        match kind.unpack() {
-            ty::TermKind::Ty(_) => self.next_ty_infer().into(),
-            ty::TermKind::Const(_) => self.next_const_infer().into(),
+    pub(super) fn next_term_infer_of_kind(&mut self, kind: I::Term) -> I::Term {
+        match kind.kind() {
+            ir::TermKind::Ty(_) => self.next_ty_infer().into(),
+            ir::TermKind::Const(_) => self.next_const_infer().into(),
         }
     }
 
@@ -631,18 +642,18 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
     #[instrument(level = "trace", skip(self), ret)]
     pub(super) fn term_is_fully_unconstrained(
         &self,
-        goal: Goal<'tcx, ty::NormalizesTo<'tcx>>,
+        goal: ir::solve::Goal<I, ir::NormalizesTo<I>>,
     ) -> bool {
-        let universe_of_term = match goal.predicate.term.unpack() {
-            ty::TermKind::Ty(ty) => {
-                if let &ty::Infer(ty::TyVar(vid)) = ty.kind() {
+        let universe_of_term = match goal.predicate.term.kind() {
+            ir::TermKind::Ty(ty) => {
+                if let ir::Infer(ir::TyVar(vid)) = ty.kind() {
                     self.infcx.universe_of_ty(vid).unwrap()
                 } else {
                     return false;
                 }
             }
-            ty::TermKind::Const(ct) => {
-                if let ty::ConstKind::Infer(ty::InferConst::Var(vid)) = ct.kind() {
+            ir::TermKind::Const(ct) => {
+                if let ir::ConstKind::Infer(ir::InferConst::Var(vid)) = ct.kind() {
                     self.infcx.universe_of_ct(vid).unwrap()
                 } else {
                     return false;
@@ -650,14 +661,14 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
             }
         };
 
-        struct ContainsTermOrNotNameable<'a, 'tcx> {
-            term: ty::Term<'tcx>,
-            universe_of_term: ty::UniverseIndex,
-            infcx: &'a InferCtxt<'tcx>,
+        struct ContainsTermOrNotNameable<'a, Infcx: InferCtxtLike<Interner = I>, I: Interner> {
+            term: I::Term,
+            universe_of_term: ir::UniverseIndex,
+            infcx: &'a Infcx,
         }
 
-        impl<'a, 'tcx> ContainsTermOrNotNameable<'a, 'tcx> {
-            fn check_nameable(&self, universe: ty::UniverseIndex) -> ControlFlow<()> {
+        impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> ContainsTermOrNotNameable<'_, Infcx, I> {
+            fn check_nameable(&self, universe: ir::UniverseIndex) -> ControlFlow<()> {
                 if self.universe_of_term.can_name(universe) {
                     ControlFlow::Continue(())
                 } else {
@@ -666,21 +677,23 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
             }
         }
 
-        impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ContainsTermOrNotNameable<'_, 'tcx> {
+        impl<Infcx: InferCtxtLike<Interner = I>, I: Interner> TypeVisitor<I>
+            for ContainsTermOrNotNameable<'_, Infcx, I>
+        {
             type Result = ControlFlow<()>;
-            fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
-                match *t.kind() {
-                    ty::Infer(ty::TyVar(vid)) => {
-                        if let ty::TermKind::Ty(term) = self.term.unpack()
-                            && let Some(term_vid) = term.ty_vid()
-                            && self.infcx.root_var(vid) == self.infcx.root_var(term_vid)
+            fn visit_ty(&mut self, t: I::Ty) -> Self::Result {
+                match t.kind() {
+                    ir::Infer(ir::TyVar(vid)) => {
+                        if let ir::TermKind::Ty(term) = self.term.kind()
+                            && let ir::Infer(ir::TyVar(term_vid)) = term.kind()
+                            && self.infcx.root_ty_var(vid) == self.infcx.root_ty_var(term_vid)
                         {
                             ControlFlow::Break(())
                         } else {
                             self.check_nameable(self.infcx.universe_of_ty(vid).unwrap())
                         }
                     }
-                    ty::Placeholder(p) => self.check_nameable(p.universe),
+                    ir::Placeholder(p) => self.check_nameable(p.universe()),
                     _ => {
                         if t.has_non_region_infer() || t.has_placeholders() {
                             t.super_visit_with(self)
@@ -691,11 +704,11 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
                 }
             }
 
-            fn visit_const(&mut self, c: ty::Const<'tcx>) -> Self::Result {
+            fn visit_const(&mut self, c: I::Const) -> Self::Result {
                 match c.kind() {
-                    ty::ConstKind::Infer(ty::InferConst::Var(vid)) => {
-                        if let ty::TermKind::Const(term) = self.term.unpack()
-                            && let ty::ConstKind::Infer(ty::InferConst::Var(term_vid)) = term.kind()
+                    ir::ConstKind::Infer(ir::InferConst::Var(vid)) => {
+                        if let ir::TermKind::Const(term) = self.term.kind()
+                            && let ir::ConstKind::Infer(ir::InferConst::Var(term_vid)) = term.kind()
                             && self.infcx.root_const_var(vid) == self.infcx.root_const_var(term_vid)
                         {
                             ControlFlow::Break(())
@@ -703,7 +716,7 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
                             self.check_nameable(self.infcx.universe_of_ct(vid).unwrap())
                         }
                     }
-                    ty::ConstKind::Placeholder(p) => self.check_nameable(p.universe),
+                    ir::ConstKind::Placeholder(p) => self.check_nameable(p.universe()),
                     _ => {
                         if c.has_non_region_infer() || c.has_placeholders() {
                             c.super_visit_with(self)
@@ -725,23 +738,13 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
     }
 
     #[instrument(level = "trace", skip(self, param_env), ret)]
-    pub(super) fn eq<T: ToTrace<'tcx>>(
+    pub(super) fn eq<T: Relate<I>>(
         &mut self,
-        param_env: ty::ParamEnv<'tcx>,
+        param_env: I::ParamEnv,
         lhs: T,
         rhs: T,
     ) -> Result<(), NoSolution> {
-        self.infcx
-            .at(&ObligationCause::dummy(), param_env)
-            // New solver ignores DefineOpaqueTypes, so choose Yes for consistency
-            .eq(DefineOpaqueTypes::Yes, lhs, rhs)
-            .map(|InferOk { value: (), obligations }| {
-                self.add_goals(GoalSource::Misc, obligations.into_iter().map(|o| o.into()));
-            })
-            .map_err(|e| {
-                trace!(?e, "failed to equate");
-                NoSolution
-            })
+        self.relate(param_env, lhs, ir::Variance::Invariant, rhs)
     }
 
     /// This should be used when relating a rigid alias with another type.
@@ -752,10 +755,10 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
     #[instrument(level = "trace", skip(self, param_env), ret)]
     pub(super) fn relate_rigid_alias_non_alias(
         &mut self,
-        param_env: ty::ParamEnv<'tcx>,
-        alias: ty::AliasTerm<'tcx>,
-        variance: ty::Variance,
-        term: ty::Term<'tcx>,
+        param_env: I::ParamEnv,
+        alias: ir::AliasTerm<I>,
+        variance: ir::Variance,
+        term: I::Term,
     ) -> Result<(), NoSolution> {
         // NOTE: this check is purely an optimization, the structural eq would
         // always fail if the term is not an inference variable.
@@ -770,12 +773,10 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
             // Alternatively we could modify `Equate` for this case by adding another
             // variant to `StructurallyRelateAliases`.
             let identity_args = self.fresh_args_for_item(alias.def_id);
-            let rigid_ctor = ty::AliasTerm::new(tcx, alias.def_id, identity_args);
+            let rigid_ctor = ir::AliasTerm::new(tcx, alias.def_id, identity_args);
             let ctor_term = rigid_ctor.to_term(tcx);
-            let InferOk { value: (), obligations } = self
-                .infcx
-                .at(&ObligationCause::dummy(), param_env)
-                .eq_structurally_relating_aliases(term, ctor_term)?;
+            let obligations =
+                self.infcx.eq_structurally_relating_aliases(param_env, term, ctor_term)?;
             debug_assert!(obligations.is_empty());
             self.relate(param_env, alias, variance, rigid_ctor)
         } else {
@@ -787,58 +788,38 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
     /// unconstrained "return value" or when we're sure that all aliases in
     /// the types are rigid.
     #[instrument(level = "trace", skip(self, param_env), ret)]
-    pub(super) fn eq_structurally_relating_aliases<T: ToTrace<'tcx>>(
+    pub(super) fn eq_structurally_relating_aliases<T: Relate<I>>(
         &mut self,
-        param_env: ty::ParamEnv<'tcx>,
+        param_env: I::ParamEnv,
         lhs: T,
         rhs: T,
     ) -> Result<(), NoSolution> {
-        let cause = ObligationCause::dummy();
-        let InferOk { value: (), obligations } =
-            self.infcx.at(&cause, param_env).eq_structurally_relating_aliases(lhs, rhs)?;
-        assert!(obligations.is_empty());
+        let result = self.infcx.eq_structurally_relating_aliases(param_env, lhs, rhs)?;
+        assert_eq!(result, vec![]);
         Ok(())
     }
 
     #[instrument(level = "trace", skip(self, param_env), ret)]
-    pub(super) fn sub<T: ToTrace<'tcx>>(
+    pub(super) fn sub<T: Relate<I>>(
         &mut self,
-        param_env: ty::ParamEnv<'tcx>,
+        param_env: I::ParamEnv,
         sub: T,
         sup: T,
     ) -> Result<(), NoSolution> {
-        self.infcx
-            .at(&ObligationCause::dummy(), param_env)
-            // New solver ignores DefineOpaqueTypes, so choose Yes for consistency
-            .sub(DefineOpaqueTypes::Yes, sub, sup)
-            .map(|InferOk { value: (), obligations }| {
-                self.add_goals(GoalSource::Misc, obligations.into_iter().map(|o| o.into()));
-            })
-            .map_err(|e| {
-                trace!(?e, "failed to subtype");
-                NoSolution
-            })
+        self.relate(param_env, sub, ir::Variance::Covariant, sup)
     }
 
     #[instrument(level = "trace", skip(self, param_env), ret)]
-    pub(super) fn relate<T: ToTrace<'tcx>>(
+    pub(super) fn relate<T: Relate<I>>(
         &mut self,
-        param_env: ty::ParamEnv<'tcx>,
+        param_env: I::ParamEnv,
         lhs: T,
-        variance: ty::Variance,
+        variance: ir::Variance,
         rhs: T,
     ) -> Result<(), NoSolution> {
-        self.infcx
-            .at(&ObligationCause::dummy(), param_env)
-            // New solver ignores DefineOpaqueTypes, so choose Yes for consistency
-            .relate(DefineOpaqueTypes::Yes, lhs, variance, rhs)
-            .map(|InferOk { value: (), obligations }| {
-                self.add_goals(GoalSource::Misc, obligations.into_iter().map(|o| o.into()));
-            })
-            .map_err(|e| {
-                trace!(?e, "failed to relate");
-                NoSolution
-            })
+        let goals = self.infcx.relate(param_env, lhs, variance, rhs)?;
+        self.add_goals(GoalSource::Misc, goals);
+        Ok(())
     }
 
     /// Equates two values returning the nested goals without adding them
@@ -847,58 +828,47 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
     /// If possible, try using `eq` instead which automatically handles nested
     /// goals correctly.
     #[instrument(level = "trace", skip(self, param_env), ret)]
-    pub(super) fn eq_and_get_goals<T: ToTrace<'tcx>>(
+    pub(super) fn eq_and_get_goals<T: Relate<I>>(
         &self,
-        param_env: ty::ParamEnv<'tcx>,
+        param_env: I::ParamEnv,
         lhs: T,
         rhs: T,
-    ) -> Result<Vec<Goal<'tcx, ty::Predicate<'tcx>>>, NoSolution> {
-        self.infcx
-            .at(&ObligationCause::dummy(), param_env)
-            // New solver ignores DefineOpaqueTypes, so choose Yes for consistency
-            .eq(DefineOpaqueTypes::Yes, lhs, rhs)
-            .map(|InferOk { value: (), obligations }| {
-                obligations.into_iter().map(|o| o.into()).collect()
-            })
-            .map_err(|e| {
-                trace!(?e, "failed to equate");
-                NoSolution
-            })
+    ) -> Result<Vec<ir::solve::Goal<I, I::Predicate>>, NoSolution> {
+        self.infcx.relate(param_env, lhs, ir::Variance::Invariant, rhs)
     }
 
-    pub(super) fn instantiate_binder_with_infer<T: TypeFoldable<TyCtxt<'tcx>> + Copy>(
+    pub(super) fn instantiate_binder_with_infer<T: TypeFoldable<I> + Copy>(
         &self,
-        value: ty::Binder<'tcx, T>,
+        value: ir::Binder<I, T>,
     ) -> T {
-        self.infcx.instantiate_binder_with_fresh_vars(
-            DUMMY_SP,
-            BoundRegionConversionTime::HigherRankedType,
-            value,
-        )
+        self.infcx.instantiate_binder_with_infer(value)
     }
 
-    pub(super) fn enter_forall<T: TypeFoldable<TyCtxt<'tcx>> + Copy, U>(
+    pub(super) fn enter_forall<T: TypeFoldable<I> + Copy, U>(
         &self,
-        value: ty::Binder<'tcx, T>,
+        value: ir::Binder<I, T>,
         f: impl FnOnce(T) -> U,
     ) -> U {
         self.infcx.enter_forall(value, f)
     }
+
     pub(super) fn resolve_vars_if_possible<T>(&self, value: T) -> T
     where
-        T: TypeFoldable<TyCtxt<'tcx>>,
+        T: TypeFoldable<I>,
     {
         self.infcx.resolve_vars_if_possible(value)
     }
 
-    pub(super) fn fresh_args_for_item(&mut self, def_id: DefId) -> ty::GenericArgsRef<'tcx> {
-        let args = self.infcx.fresh_args_for_item(DUMMY_SP, def_id);
+    pub(super) fn fresh_args_for_item(&mut self, def_id: I::DefId) -> I::GenericArgs {
+        let args = self.infcx.fresh_args_for_item(def_id);
         for arg in args {
             self.inspect.add_var_value(arg);
         }
         args
     }
+}
 
+impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
     pub(super) fn register_ty_outlives(&self, ty: Ty<'tcx>, lt: ty::Region<'tcx>) {
         self.infcx.register_region_obligation_with_cause(ty, lt, &ObligationCause::dummy());
     }
@@ -1096,28 +1066,36 @@ impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
 ///
 /// This is a performance optimization to more eagerly detect cycles during trait
 /// solving. See tests/ui/traits/next-solver/cycles/cycle-modulo-ambig-aliases.rs.
-struct ReplaceAliasWithInfer<'me, 'a, 'tcx> {
-    ecx: &'me mut EvalCtxt<'a, InferCtxt<'tcx>>,
-    param_env: ty::ParamEnv<'tcx>,
+struct ReplaceAliasWithInfer<'me, 'a, Infcx, I>
+where
+    Infcx: InferCtxtLike<Interner = I>,
+    I: Interner,
+{
+    ecx: &'me mut EvalCtxt<'a, Infcx>,
+    param_env: I::ParamEnv,
 }
 
-impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReplaceAliasWithInfer<'_, '_, 'tcx> {
-    fn interner(&self) -> TyCtxt<'tcx> {
+impl<Infcx, I> TypeFolder<I> for ReplaceAliasWithInfer<'_, '_, Infcx, I>
+where
+    Infcx: InferCtxtLike<Interner = I>,
+    I: Interner,
+{
+    fn interner(&self) -> I {
         self.ecx.interner()
     }
 
-    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
-        match *ty.kind() {
-            ty::Alias(..) if !ty.has_escaping_bound_vars() => {
+    fn fold_ty(&mut self, ty: I::Ty) -> I::Ty {
+        match ty.kind() {
+            ir::Alias(..) if !ty.has_escaping_bound_vars() => {
                 let infer_ty = self.ecx.next_ty_infer();
-                let normalizes_to = ty::PredicateKind::AliasRelate(
+                let normalizes_to = ir::PredicateKind::AliasRelate(
                     ty.into(),
                     infer_ty.into(),
                     AliasRelationDirection::Equate,
                 );
                 self.ecx.add_goal(
                     GoalSource::Misc,
-                    Goal::new(self.interner(), self.param_env, normalizes_to),
+                    ir::solve::Goal::new(self.interner(), self.param_env, normalizes_to),
                 );
                 infer_ty
             }
@@ -1125,18 +1103,18 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReplaceAliasWithInfer<'_, '_, 'tcx> {
         }
     }
 
-    fn fold_const(&mut self, ct: ty::Const<'tcx>) -> ty::Const<'tcx> {
+    fn fold_const(&mut self, ct: I::Const) -> I::Const {
         match ct.kind() {
-            ty::ConstKind::Unevaluated(..) if !ct.has_escaping_bound_vars() => {
+            ir::ConstKind::Unevaluated(..) if !ct.has_escaping_bound_vars() => {
                 let infer_ct = self.ecx.next_const_infer();
-                let normalizes_to = ty::PredicateKind::AliasRelate(
+                let normalizes_to = ir::PredicateKind::AliasRelate(
                     ct.into(),
                     infer_ct.into(),
                     AliasRelationDirection::Equate,
                 );
                 self.ecx.add_goal(
                     GoalSource::Misc,
-                    Goal::new(self.interner(), self.param_env, normalizes_to),
+                    ir::solve::Goal::new(self.interner(), self.param_env, normalizes_to),
                 );
                 infer_ct
             }
@@ -1144,7 +1122,7 @@ impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReplaceAliasWithInfer<'_, '_, 'tcx> {
         }
     }
 
-    fn fold_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
+    fn fold_predicate(&mut self, predicate: I::Predicate) -> I::Predicate {
         if predicate.allow_normalization() { predicate.super_fold_with(self) } else { predicate }
     }
 }
diff --git a/compiler/rustc_trait_selection/src/solve/inspect/build.rs b/compiler/rustc_trait_selection/src/solve/inspect/build.rs
index 84c04900ae484..35750598bc740 100644
--- a/compiler/rustc_trait_selection/src/solve/inspect/build.rs
+++ b/compiler/rustc_trait_selection/src/solve/inspect/build.rs
@@ -34,10 +34,11 @@ use rustc_type_ir::{self as ty, InferCtxtLike, Interner};
 /// trees. At the end of trait solving `ProofTreeBuilder::finalize`
 /// is called to recursively convert the whole structure to a
 /// finished proof tree.
-pub(in crate::solve) struct ProofTreeBuilder<
+pub(in crate::solve) struct ProofTreeBuilder<Infcx, I = <Infcx as InferCtxtLike>::Interner>
+where
     Infcx: InferCtxtLike<Interner = I>,
-    I: Interner = <Infcx as InferCtxtLike>::Interner,
-> {
+    I: Interner,
+{
     _infcx: PhantomData<Infcx>,
     state: Option<Box<DebugSolver<I>>>,
 }
diff --git a/compiler/rustc_trait_selection/src/solve/mod.rs b/compiler/rustc_trait_selection/src/solve/mod.rs
index c47b01949641b..fdcf4ff11e468 100644
--- a/compiler/rustc_trait_selection/src/solve/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/mod.rs
@@ -235,17 +235,6 @@ impl<'a, 'tcx> EvalCtxt<'a, InferCtxt<'tcx>> {
 }
 
 impl<'tcx> EvalCtxt<'_, InferCtxt<'tcx>> {
-    #[instrument(level = "trace", skip(self, goals))]
-    fn add_goals(
-        &mut self,
-        source: GoalSource,
-        goals: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
-    ) {
-        for goal in goals {
-            self.add_goal(source, goal);
-        }
-    }
-
     /// Try to merge multiple possible ways to prove a goal, if that is not possible returns `None`.
     ///
     /// In this case we tend to flounder and return ambiguity by calling `[EvalCtxt::flounder]`.
diff --git a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
index 787f08a084ee6..50253d815283a 100644
--- a/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
+++ b/compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
@@ -17,7 +17,7 @@ use rustc_middle::ty::NormalizesTo;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::ty::{TypeVisitableExt, Upcast};
 use rustc_middle::{bug, span_bug};
-use rustc_span::{sym, ErrorGuaranteed, DUMMY_SP};
+use rustc_span::{ErrorGuaranteed, DUMMY_SP};
 
 mod anon_const;
 mod inherent;
@@ -719,13 +719,16 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
 
         let coroutine = args.as_coroutine();
 
-        let name = tcx.associated_item(goal.predicate.def_id()).name;
-        let term = if name == sym::Return {
+        let lang_items = tcx.lang_items();
+        let term = if Some(goal.predicate.def_id()) == lang_items.coroutine_return() {
             coroutine.return_ty().into()
-        } else if name == sym::Yield {
+        } else if Some(goal.predicate.def_id()) == lang_items.coroutine_yield() {
             coroutine.yield_ty().into()
         } else {
-            bug!("unexpected associated item `<{self_ty} as Coroutine>::{name}`")
+            bug!(
+                "unexpected associated item `<{self_ty} as Coroutine>::{}`",
+                tcx.item_name(goal.predicate.def_id())
+            )
         };
 
         Self::probe_and_consider_implied_clause(
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 2c9cb79664b34..32409e13842e0 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1373,15 +1373,16 @@ fn confirm_coroutine_candidate<'cx, 'tcx>(
         coroutine_sig,
     );
 
-    let name = tcx.associated_item(obligation.predicate.def_id).name;
-    let ty = if name == sym::Return {
+    let lang_items = tcx.lang_items();
+    let ty = if Some(obligation.predicate.def_id) == lang_items.coroutine_return() {
         return_ty
-    } else if name == sym::Yield {
+    } else if Some(obligation.predicate.def_id) == lang_items.coroutine_yield() {
         yield_ty
     } else {
         span_bug!(
             tcx.def_span(obligation.predicate.def_id),
-            "unexpected associated type: `Coroutine::{name}`"
+            "unexpected associated type: `Coroutine::{}`",
+            tcx.item_name(obligation.predicate.def_id),
         );
     };
 
diff --git a/compiler/rustc_type_ir/src/infcx.rs b/compiler/rustc_type_ir/src/infcx.rs
index 24e10722448cc..92a717a0d9efb 100644
--- a/compiler/rustc_type_ir/src/infcx.rs
+++ b/compiler/rustc_type_ir/src/infcx.rs
@@ -1,23 +1,75 @@
-use crate::{ConstVid, EffectVid, FloatVid, IntVid, Interner, RegionVid, TyVid, UniverseIndex};
+use crate::fold::TypeFoldable;
+use crate::relate::Relate;
+use crate::solve::{Goal, NoSolution};
+use crate::{self as ty, Interner};
 
-pub trait InferCtxtLike {
+pub trait InferCtxtLike: Sized {
     type Interner: Interner;
 
     fn interner(&self) -> Self::Interner;
 
-    fn universe_of_ty(&self, ty: TyVid) -> Option<UniverseIndex>;
-    fn universe_of_lt(&self, lt: RegionVid) -> Option<UniverseIndex>;
-    fn universe_of_ct(&self, ct: ConstVid) -> Option<UniverseIndex>;
+    fn universe_of_ty(&self, ty: ty::TyVid) -> Option<ty::UniverseIndex>;
+    fn universe_of_lt(&self, lt: ty::RegionVid) -> Option<ty::UniverseIndex>;
+    fn universe_of_ct(&self, ct: ty::ConstVid) -> Option<ty::UniverseIndex>;
 
-    fn opportunistic_resolve_ty_var(&self, vid: TyVid) -> <Self::Interner as Interner>::Ty;
-    fn opportunistic_resolve_int_var(&self, vid: IntVid) -> <Self::Interner as Interner>::Ty;
-    fn opportunistic_resolve_float_var(&self, vid: FloatVid) -> <Self::Interner as Interner>::Ty;
-    fn opportunistic_resolve_ct_var(&self, vid: ConstVid) -> <Self::Interner as Interner>::Const;
+    fn root_ty_var(&self, var: ty::TyVid) -> ty::TyVid;
+    fn root_const_var(&self, var: ty::ConstVid) -> ty::ConstVid;
+
+    fn opportunistic_resolve_ty_var(&self, vid: ty::TyVid) -> <Self::Interner as Interner>::Ty;
+    fn opportunistic_resolve_int_var(&self, vid: ty::IntVid) -> <Self::Interner as Interner>::Ty;
+    fn opportunistic_resolve_float_var(
+        &self,
+        vid: ty::FloatVid,
+    ) -> <Self::Interner as Interner>::Ty;
+    fn opportunistic_resolve_ct_var(
+        &self,
+        vid: ty::ConstVid,
+    ) -> <Self::Interner as Interner>::Const;
     fn opportunistic_resolve_effect_var(
         &self,
-        vid: EffectVid,
+        vid: ty::EffectVid,
     ) -> <Self::Interner as Interner>::Const;
-    fn opportunistic_resolve_lt_var(&self, vid: RegionVid) -> <Self::Interner as Interner>::Region;
+    fn opportunistic_resolve_lt_var(
+        &self,
+        vid: ty::RegionVid,
+    ) -> <Self::Interner as Interner>::Region;
 
     fn defining_opaque_types(&self) -> <Self::Interner as Interner>::DefiningOpaqueTypes;
+
+    fn next_ty_infer(&self) -> <Self::Interner as Interner>::Ty;
+    fn next_const_infer(&self) -> <Self::Interner as Interner>::Const;
+    fn fresh_args_for_item(
+        &self,
+        def_id: <Self::Interner as Interner>::DefId,
+    ) -> <Self::Interner as Interner>::GenericArgs;
+
+    fn instantiate_binder_with_infer<T: TypeFoldable<Self::Interner> + Copy>(
+        &self,
+        value: ty::Binder<Self::Interner, T>,
+    ) -> T;
+
+    fn enter_forall<T: TypeFoldable<Self::Interner> + Copy, U>(
+        &self,
+        value: ty::Binder<Self::Interner, T>,
+        f: impl FnOnce(T) -> U,
+    ) -> U;
+
+    fn relate<T: Relate<Self::Interner>>(
+        &self,
+        param_env: <Self::Interner as Interner>::ParamEnv,
+        lhs: T,
+        variance: ty::Variance,
+        rhs: T,
+    ) -> Result<Vec<Goal<Self::Interner, <Self::Interner as Interner>::Predicate>>, NoSolution>;
+
+    fn eq_structurally_relating_aliases<T: Relate<Self::Interner>>(
+        &self,
+        param_env: <Self::Interner as Interner>::ParamEnv,
+        lhs: T,
+        rhs: T,
+    ) -> Result<Vec<Goal<Self::Interner, <Self::Interner as Interner>::Predicate>>, NoSolution>;
+
+    fn resolve_vars_if_possible<T>(&self, value: T) -> T
+    where
+        T: TypeFoldable<Self::Interner>;
 }
diff --git a/compiler/rustc_type_ir/src/inherent.rs b/compiler/rustc_type_ir/src/inherent.rs
index 2fc765f1c8fae..6b84592978a26 100644
--- a/compiler/rustc_type_ir/src/inherent.rs
+++ b/compiler/rustc_type_ir/src/inherent.rs
@@ -29,6 +29,8 @@ pub trait Ty<I: Interner<Ty = Self>>:
 {
     fn new_bool(interner: I) -> Self;
 
+    fn new_u8(interner: I) -> Self;
+
     fn new_infer(interner: I, var: ty::InferTy) -> Self;
 
     fn new_var(interner: I, var: ty::TyVid) -> Self;
@@ -39,6 +41,18 @@ pub trait Ty<I: Interner<Ty = Self>>:
 
     fn new_alias(interner: I, kind: ty::AliasTyKind, alias_ty: ty::AliasTy<I>) -> Self;
 
+    fn new_projection(
+        interner: I,
+        def_id: I::DefId,
+        args: impl IntoIterator<Item: Into<I::GenericArg>>,
+    ) -> Self {
+        Ty::new_alias(
+            interner,
+            ty::AliasTyKind::Projection,
+            ty::AliasTy::new(interner, def_id, args),
+        )
+    }
+
     fn new_error(interner: I, guar: I::ErrorGuaranteed) -> Self;
 
     fn new_adt(interner: I, adt_def: I::AdtDef, args: I::GenericArgs) -> Self;
@@ -75,6 +89,12 @@ pub trait Ty<I: Interner<Ty = Self>>:
         It: Iterator<Item = T>,
         T: CollectAndApply<Self, Self>;
 
+    fn new_fn_def(interner: I, def_id: I::DefId, args: I::GenericArgs) -> Self;
+
+    fn new_fn_ptr(interner: I, sig: ty::Binder<I, ty::FnSig<I>>) -> Self;
+
+    fn new_pat(interner: I, ty: Self, pat: I::Pat) -> Self;
+
     fn tuple_fields(self) -> I::Tys;
 
     fn to_opt_closure_kind(self) -> Option<ty::ClosureKind>;
@@ -83,11 +103,29 @@ pub trait Ty<I: Interner<Ty = Self>>:
 
     fn from_coroutine_closure_kind(interner: I, kind: ty::ClosureKind) -> Self;
 
-    fn new_fn_def(interner: I, def_id: I::DefId, args: I::GenericArgs) -> Self;
-
-    fn new_fn_ptr(interner: I, sig: ty::Binder<I, ty::FnSig<I>>) -> Self;
-
-    fn new_pat(interner: I, ty: Self, pat: I::Pat) -> Self;
+    fn is_ty_var(self) -> bool {
+        matches!(self.kind(), ty::Infer(ty::TyVar(_)))
+    }
+
+    fn fn_sig(self, interner: I) -> ty::Binder<I, ty::FnSig<I>> {
+        match self.kind() {
+            ty::FnPtr(sig) => sig,
+            ty::FnDef(def_id, args) => interner.fn_sig(def_id).instantiate(interner, &args),
+            ty::Error(_) => {
+                // ignore errors (#54954)
+                ty::Binder::dummy(ty::FnSig {
+                    inputs_and_output: Default::default(),
+                    c_variadic: false,
+                    safety: I::Safety::safe(),
+                    abi: I::Abi::rust(),
+                })
+            }
+            ty::Closure(..) => panic!(
+                "to get the signature of a closure, use `args.as_closure().sig()` not `fn_sig()`",
+            ),
+            _ => panic!("Ty::fn_sig() called on non-fn type: {:?}", self),
+        }
+    }
 }
 
 pub trait Tys<I: Interner<Tys = Self>>:
@@ -103,12 +141,16 @@ pub trait Tys<I: Interner<Tys = Self>>:
     fn split_inputs_and_output(self) -> (I::FnInputTys, I::Ty);
 }
 
-pub trait Abi<I: Interner<Abi = Self>>: Copy + Debug + Hash + Eq + TypeVisitable<I> {
+pub trait Abi<I: Interner<Abi = Self>>: Copy + Debug + Hash + Eq + Relate<I> {
+    fn rust() -> Self;
+
     /// Whether this ABI is `extern "Rust"`.
     fn is_rust(self) -> bool;
 }
 
-pub trait Safety<I: Interner<Safety = Self>>: Copy + Debug + Hash + Eq + TypeVisitable<I> {
+pub trait Safety<I: Interner<Safety = Self>>: Copy + Debug + Hash + Eq + Relate<I> {
+    fn safe() -> Self;
+
     fn is_safe(self) -> bool;
 
     fn prefix_str(self) -> &'static str;
@@ -122,7 +164,6 @@ pub trait Region<I: Interner<Region = Self>>:
     + Into<I::GenericArg>
     + IntoKind<Kind = ty::RegionKind<I>>
     + Flags
-    + TypeVisitable<I>
     + Relate<I>
 {
     fn new_bound(interner: I, debruijn: ty::DebruijnIndex, var: I::BoundRegion) -> Self;
@@ -158,12 +199,57 @@ pub trait Const<I: Interner<Const = Self>>:
     fn new_unevaluated(interner: I, uv: ty::UnevaluatedConst<I>) -> Self;
 
     fn new_expr(interner: I, expr: I::ExprConst) -> Self;
+
+    fn is_ct_var(self) -> bool {
+        matches!(self.kind(), ty::ConstKind::Infer(ty::InferConst::Var(_)))
+    }
 }
 
 pub trait GenericsOf<I: Interner<GenericsOf = Self>> {
     fn count(&self) -> usize;
 }
 
+pub trait GenericArg<I: Interner<GenericArg = Self>>:
+    Copy
+    + Debug
+    + Hash
+    + Eq
+    + IntoKind<Kind = ty::GenericArgKind<I>>
+    + TypeVisitable<I>
+    + Relate<I>
+    + From<I::Ty>
+    + From<I::Region>
+    + From<I::Const>
+{
+}
+
+pub trait Term<I: Interner<Term = Self>>:
+    Copy + Debug + Hash + Eq + IntoKind<Kind = ty::TermKind<I>> + TypeFoldable<I> + Relate<I>
+{
+    fn as_type(&self) -> Option<I::Ty> {
+        if let ty::TermKind::Ty(ty) = self.kind() { Some(ty) } else { None }
+    }
+
+    fn expect_type(&self) -> I::Ty {
+        self.as_type().expect("expected a type, but found a const")
+    }
+
+    fn as_const(&self) -> Option<I::Const> {
+        if let ty::TermKind::Const(c) = self.kind() { Some(c) } else { None }
+    }
+
+    fn expect_const(&self) -> I::Const {
+        self.as_const().expect("expected a const, but found a type")
+    }
+
+    fn is_infer(self) -> bool {
+        match self.kind() {
+            ty::TermKind::Ty(ty) => ty.is_ty_var(),
+            ty::TermKind::Const(ct) => ct.is_ct_var(),
+        }
+    }
+}
+
 pub trait GenericArgs<I: Interner<GenericArgs = Self>>:
     Copy
     + Debug
@@ -172,7 +258,6 @@ pub trait GenericArgs<I: Interner<GenericArgs = Self>>:
     + IntoIterator<Item = I::GenericArg>
     + Deref<Target: Deref<Target = [I::GenericArg]>>
     + Default
-    + TypeFoldable<I>
     + Relate<I>
 {
     fn type_at(self, i: usize) -> I::Ty;
@@ -188,6 +273,16 @@ pub trait GenericArgs<I: Interner<GenericArgs = Self>>:
     fn split_closure_args(self) -> ty::ClosureArgsParts<I>;
     fn split_coroutine_closure_args(self) -> ty::CoroutineClosureArgsParts<I>;
     fn split_coroutine_args(self) -> ty::CoroutineArgsParts<I>;
+
+    fn as_closure(self) -> ty::ClosureArgs<I> {
+        ty::ClosureArgs { args: self }
+    }
+    fn as_coroutine_closure(self) -> ty::CoroutineClosureArgs<I> {
+        ty::CoroutineClosureArgs { args: self }
+    }
+    fn as_coroutine(self) -> ty::CoroutineArgs<I> {
+        ty::CoroutineArgs { args: self }
+    }
 }
 
 pub trait Predicate<I: Interner<Predicate = Self>>:
@@ -198,9 +293,20 @@ pub trait Predicate<I: Interner<Predicate = Self>>:
     + TypeSuperVisitable<I>
     + TypeSuperFoldable<I>
     + Flags
+    + UpcastFrom<I, ty::PredicateKind<I>>
+    + UpcastFrom<I, ty::Binder<I, ty::PredicateKind<I>>>
+    + UpcastFrom<I, ty::ClauseKind<I>>
+    + UpcastFrom<I, ty::Binder<I, ty::ClauseKind<I>>>
+    + UpcastFrom<I, I::Clause>
     + UpcastFrom<I, ty::NormalizesTo<I>>
+    + UpcastFrom<I, ty::TraitRef<I>>
+    + UpcastFrom<I, ty::Binder<I, ty::TraitRef<I>>>
+    + IntoKind<Kind = ty::Binder<I, ty::PredicateKind<I>>>
 {
     fn is_coinductive(self, interner: I) -> bool;
+
+    // FIXME: Eventually uplift the impl out of rustc and make this defaulted.
+    fn allow_normalization(self) -> bool;
 }
 
 pub trait Clause<I: Interner<Clause = Self>>:
@@ -208,6 +314,7 @@ pub trait Clause<I: Interner<Clause = Self>>:
     + Debug
     + Hash
     + Eq
+    + TypeFoldable<I>
     // FIXME: Remove these, uplift the `Upcast` impls.
     + UpcastFrom<I, ty::Binder<I, ty::TraitRef<I>>>
     + UpcastFrom<I, ty::Binder<I, ty::ProjectionPredicate<I>>>
@@ -242,8 +349,17 @@ pub trait ParamLike {
 
 pub trait AdtDef<I: Interner>: Copy + Debug + Hash + Eq {
     fn def_id(self) -> I::DefId;
+
+    fn is_phantom_data(self) -> bool;
+
+    // FIXME: perhaps use `all_fields` and expose `FieldDef`.
+    fn all_field_tys(self, interner: I) -> ty::EarlyBinder<I, impl Iterator<Item = I::Ty>>;
+
+    fn sized_constraint(self, interner: I) -> Option<ty::EarlyBinder<I, I::Ty>>;
 }
 
 pub trait Features<I: Interner>: Copy {
     fn generic_const_exprs(self) -> bool;
+
+    fn coroutine_clone(self) -> bool;
 }
diff --git a/compiler/rustc_type_ir/src/interner.rs b/compiler/rustc_type_ir/src/interner.rs
index b7f412ecb8ea9..a2b71e1fc2575 100644
--- a/compiler/rustc_type_ir/src/interner.rs
+++ b/compiler/rustc_type_ir/src/interner.rs
@@ -1,3 +1,4 @@
+use rustc_ast_ir::Movability;
 use smallvec::SmallVec;
 use std::fmt::Debug;
 use std::hash::Hash;
@@ -6,6 +7,7 @@ use std::ops::Deref;
 use crate::fold::TypeFoldable;
 use crate::inherent::*;
 use crate::ir_print::IrPrint;
+use crate::lang_items::TraitSolverLangItem;
 use crate::relate::Relate;
 use crate::solve::inspect::CanonicalGoalEvaluationStep;
 use crate::visit::{Flags, TypeSuperVisitable, TypeVisitable};
@@ -31,20 +33,8 @@ pub trait Interner:
 
     type GenericArgs: GenericArgs<Self>;
     type GenericArgsSlice: Copy + Debug + Hash + Eq + Deref<Target = [Self::GenericArg]>;
-    type GenericArg: Copy
-        + Debug
-        + Hash
-        + Eq
-        + IntoKind<Kind = ty::GenericArgKind<Self>>
-        + TypeVisitable<Self>
-        + Relate<Self>;
-    type Term: Copy
-        + Debug
-        + Hash
-        + Eq
-        + IntoKind<Kind = ty::TermKind<Self>>
-        + TypeFoldable<Self>
-        + Relate<Self>;
+    type GenericArg: GenericArg<Self>;
+    type Term: Term<Self>;
 
     type BoundVarKinds: Copy
         + Debug
@@ -74,11 +64,16 @@ pub trait Interner:
 
     // Things stored inside of tys
     type ErrorGuaranteed: Copy + Debug + Hash + Eq;
-    type BoundExistentialPredicates: Copy + Debug + Hash + Eq + Relate<Self>;
+    type BoundExistentialPredicates: Copy
+        + Debug
+        + Hash
+        + Eq
+        + Relate<Self>
+        + IntoIterator<Item = ty::Binder<Self, ty::ExistentialPredicate<Self>>>;
     type AllocId: Copy + Debug + Hash + Eq;
     type Pat: Copy + Debug + Hash + Eq + Debug + Relate<Self>;
-    type Safety: Safety<Self> + TypeFoldable<Self> + Relate<Self>;
-    type Abi: Abi<Self> + TypeFoldable<Self> + Relate<Self>;
+    type Safety: Safety<Self>;
+    type Abi: Abi<Self>;
 
     // Kinds of consts
     type Const: Const<Self>;
@@ -153,6 +148,38 @@ pub trait Interner:
 
     type Features: Features<Self>;
     fn features(self) -> Self::Features;
+
+    fn bound_coroutine_hidden_types(
+        self,
+        def_id: Self::DefId,
+    ) -> impl IntoIterator<Item = ty::EarlyBinder<Self, ty::Binder<Self, Self::Ty>>>;
+
+    fn fn_sig(
+        self,
+        def_id: Self::DefId,
+    ) -> ty::EarlyBinder<Self, ty::Binder<Self, ty::FnSig<Self>>>;
+
+    fn coroutine_movability(self, def_id: Self::DefId) -> Movability;
+
+    fn coroutine_for_closure(self, def_id: Self::DefId) -> Self::DefId;
+
+    fn generics_require_sized_self(self, def_id: Self::DefId) -> bool;
+
+    fn item_bounds(
+        self,
+        def_id: Self::DefId,
+    ) -> ty::EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>>;
+
+    fn super_predicates_of(
+        self,
+        def_id: Self::DefId,
+    ) -> ty::EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>>;
+
+    fn has_target_features(self, def_id: Self::DefId) -> bool;
+
+    fn require_lang_item(self, lang_item: TraitSolverLangItem) -> Self::DefId;
+
+    fn associated_type_def_ids(self, def_id: Self::DefId) -> impl IntoIterator<Item = Self::DefId>;
 }
 
 /// Imagine you have a function `F: FnOnce(&[T]) -> R`, plus an iterator `iter`
diff --git a/compiler/rustc_type_ir/src/lang_items.rs b/compiler/rustc_type_ir/src/lang_items.rs
new file mode 100644
index 0000000000000..9a3b324fcd765
--- /dev/null
+++ b/compiler/rustc_type_ir/src/lang_items.rs
@@ -0,0 +1,8 @@
+/// Lang items used by the new trait solver. This can be mapped to whatever internal
+/// representation of `LangItem`s used in the underlying compiler implementation.
+pub enum TraitSolverLangItem {
+    Future,
+    FutureOutput,
+    AsyncFnKindHelper,
+    AsyncFnKindUpvars,
+}
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index a76e278cc05d0..7f0c3df381daf 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -32,6 +32,7 @@ pub mod error;
 pub mod fold;
 pub mod inherent;
 pub mod ir_print;
+pub mod lang_items;
 pub mod lift;
 pub mod relate;
 pub mod solve;
diff --git a/library/core/src/ops/coroutine.rs b/library/core/src/ops/coroutine.rs
index 6a6c5db1ab115..753f14c6b85ec 100644
--- a/library/core/src/ops/coroutine.rs
+++ b/library/core/src/ops/coroutine.rs
@@ -76,6 +76,7 @@ pub trait Coroutine<R = ()> {
     /// values which are allowed to be returned each time a coroutine yields.
     /// For example an iterator-as-a-coroutine would likely have this type as
     /// `T`, the type being iterated over.
+    #[cfg_attr(not(bootstrap), lang = "coroutine_yield")]
     type Yield;
 
     /// The type of value this coroutine returns.
@@ -84,6 +85,7 @@ pub trait Coroutine<R = ()> {
     /// `return` statement or implicitly as the last expression of a coroutine
     /// literal. For example futures would use this as `Result<T, E>` as it
     /// represents a completed future.
+    #[cfg_attr(not(bootstrap), lang = "coroutine_return")]
     type Return;
 
     /// Resumes the execution of this coroutine.