diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index c4c54620e04e9..315303b25fe4e 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -498,11 +498,11 @@ impl<'cx, 'tcx> BorrowckInferCtxt<'cx, 'tcx> {
         let next_region = self.infcx.next_region_var(origin);
         let vid = next_region.as_var();
 
-        if cfg!(debug_assertions) && !self.inside_canonicalization_ctxt() {
+        if cfg!(debug_assertions) {
             debug!("inserting vid {:?} with origin {:?} into var_to_origin", vid, origin);
             let ctxt = get_ctxt_fn();
             let mut var_to_origin = self.reg_var_to_origin.borrow_mut();
-            var_to_origin.insert(vid, ctxt);
+            assert_eq!(var_to_origin.insert(vid, ctxt), None);
         }
 
         next_region
@@ -520,11 +520,11 @@ impl<'cx, 'tcx> BorrowckInferCtxt<'cx, 'tcx> {
         let next_region = self.infcx.next_nll_region_var(origin);
         let vid = next_region.as_var();
 
-        if cfg!(debug_assertions) && !self.inside_canonicalization_ctxt() {
+        if cfg!(debug_assertions) {
             debug!("inserting vid {:?} with origin {:?} into var_to_origin", vid, origin);
             let ctxt = get_ctxt_fn();
             let mut var_to_origin = self.reg_var_to_origin.borrow_mut();
-            var_to_origin.insert(vid, ctxt);
+            assert_eq!(var_to_origin.insert(vid, ctxt), None);
         }
 
         next_region
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
index 7e6d17ec3437e..7158c62b548af 100644
--- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs
+++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
@@ -131,9 +131,13 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
             ty::BoundRegionKind::BrEnv => BoundRegionInfo::Name(sym::env),
         };
 
-        if cfg!(debug_assertions) && !self.type_checker.infcx.inside_canonicalization_ctxt() {
+        if cfg!(debug_assertions) {
             let mut var_to_origin = self.type_checker.infcx.reg_var_to_origin.borrow_mut();
-            var_to_origin.insert(reg.as_var(), RegionCtxt::Placeholder(reg_info));
+            let new = RegionCtxt::Placeholder(reg_info);
+            let prev = var_to_origin.insert(reg.as_var(), new);
+            if let Some(prev) = prev {
+                assert_eq!(new, prev);
+            }
         }
 
         reg
@@ -146,9 +150,10 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
             universe,
         );
 
-        if cfg!(debug_assertions) && !self.type_checker.infcx.inside_canonicalization_ctxt() {
+        if cfg!(debug_assertions) {
             let mut var_to_origin = self.type_checker.infcx.reg_var_to_origin.borrow_mut();
-            var_to_origin.insert(reg.as_var(), RegionCtxt::Existential(None));
+            let prev = var_to_origin.insert(reg.as_var(), RegionCtxt::Existential(None));
+            assert_eq!(prev, None);
         }
 
         reg
diff --git a/compiler/rustc_infer/src/infer/at.rs b/compiler/rustc_infer/src/infer/at.rs
index d240d8e491faf..0c8854e962abb 100644
--- a/compiler/rustc_infer/src/infer/at.rs
+++ b/compiler/rustc_infer/src/infer/at.rs
@@ -30,8 +30,6 @@ use super::*;
 use rustc_middle::ty::relate::{Relate, TypeRelation};
 use rustc_middle::ty::{Const, ImplSubject};
 
-use std::cell::Cell;
-
 /// Whether we should define opaque types or just treat them opaquely.
 ///
 /// Currently only used to prevent predicate matching from matching anything
@@ -84,7 +82,6 @@ impl<'tcx> InferCtxt<'tcx> {
             in_snapshot: self.in_snapshot.clone(),
             universe: self.universe.clone(),
             intercrate: self.intercrate,
-            inside_canonicalization_ctxt: Cell::new(self.inside_canonicalization_ctxt()),
         }
     }
 }
diff --git a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
index d798202a64441..427d05c8b4da7 100644
--- a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
+++ b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
@@ -561,8 +561,6 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
     where
         V: TypeFoldable<TyCtxt<'tcx>>,
     {
-        let _inside_canonical_ctxt_guard = infcx.set_canonicalization_ctxt();
-
         let needs_canonical_flags = if canonicalize_region_mode.any() {
             TypeFlags::HAS_INFER |
             TypeFlags::HAS_FREE_REGIONS | // `HAS_RE_PLACEHOLDER` implies `HAS_FREE_REGIONS`
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 1cfdb791cd6ae..a89b993159902 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -39,7 +39,6 @@ use rustc_span::Span;
 
 use std::cell::{Cell, RefCell};
 use std::fmt;
-use std::ops::Drop;
 
 use self::combine::CombineFields;
 use self::error_reporting::TypeErrCtxt;
@@ -342,11 +341,6 @@ pub struct InferCtxt<'tcx> {
     /// there is no type that the user could *actually name* that
     /// would satisfy it. This avoids crippling inference, basically.
     pub intercrate: bool,
-
-    /// Flag that is set when we enter canonicalization. Used for debugging to ensure
-    /// that we only collect region information for `BorrowckInferCtxt::reg_var_to_origin`
-    /// inside non-canonicalization contexts.
-    inside_canonicalization_ctxt: Cell<bool>,
 }
 
 /// See the `error_reporting` module for more details.
@@ -638,7 +632,6 @@ impl<'tcx> InferCtxtBuilder<'tcx> {
             skip_leak_check: Cell::new(false),
             universe: Cell::new(ty::UniverseIndex::ROOT),
             intercrate,
-            inside_canonicalization_ctxt: Cell::new(false),
         }
     }
 }
@@ -1636,31 +1629,6 @@ impl<'tcx> InferCtxt<'tcx> {
             }
         }
     }
-
-    pub fn inside_canonicalization_ctxt(&self) -> bool {
-        self.inside_canonicalization_ctxt.get()
-    }
-
-    pub fn set_canonicalization_ctxt(&self) -> CanonicalizationCtxtGuard<'_, 'tcx> {
-        let prev_ctxt = self.inside_canonicalization_ctxt();
-        self.inside_canonicalization_ctxt.set(true);
-        CanonicalizationCtxtGuard { prev_ctxt, infcx: self }
-    }
-
-    fn set_canonicalization_ctxt_to(&self, ctxt: bool) {
-        self.inside_canonicalization_ctxt.set(ctxt);
-    }
-}
-
-pub struct CanonicalizationCtxtGuard<'cx, 'tcx> {
-    prev_ctxt: bool,
-    infcx: &'cx InferCtxt<'tcx>,
-}
-
-impl<'cx, 'tcx> Drop for CanonicalizationCtxtGuard<'cx, 'tcx> {
-    fn drop(&mut self) {
-        self.infcx.set_canonicalization_ctxt_to(self.prev_ctxt)
-    }
 }
 
 impl<'tcx> TypeErrCtxt<'_, 'tcx> {
diff --git a/compiler/rustc_infer/src/infer/nll_relate/mod.rs b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
index 9f7b26b87f459..88a0a81e276d2 100644
--- a/compiler/rustc_infer/src/infer/nll_relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
@@ -30,11 +30,10 @@ use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::fold::FnMutDelegate;
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
-use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor};
+use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{self, InferConst, Ty, TyCtxt};
 use rustc_span::{Span, Symbol};
 use std::fmt::Debug;
-use std::ops::ControlFlow;
 
 use super::combine::ObligationEmittingRelation;
 
@@ -115,11 +114,6 @@ pub trait TypeRelatingDelegate<'tcx> {
     fn forbid_inference_vars() -> bool;
 }
 
-#[derive(Clone, Debug, Default)]
-struct BoundRegionScope<'tcx> {
-    map: FxHashMap<ty::BoundRegion, ty::Region<'tcx>>,
-}
-
 #[derive(Copy, Clone)]
 struct UniversallyQuantified(bool);
 
@@ -230,10 +224,13 @@ where
     ) -> RelateResult<'tcx, T> {
         let universe = self.infcx.probe_ty_var(for_vid).unwrap_err();
 
+        if value.has_escaping_bound_vars() {
+            bug!("trying to instantiate {for_vid:?} with escaping bound vars: {value:?}");
+        }
+
         let mut generalizer = TypeGeneralizer {
             infcx: self.infcx,
             delegate: &mut self.delegate,
-            first_free_index: ty::INNERMOST,
             ambient_variance: self.ambient_variance,
             for_vid_sub_root: self.infcx.inner.borrow_mut().type_variables().sub_root_var(for_vid),
             universe,
@@ -488,13 +485,7 @@ where
         }
 
         if a == b {
-            // Subtle: if a or b has a bound variable that we are lazily
-            // substituting, then even if a == b, it could be that the values we
-            // will substitute for those bound variables are *not* the same, and
-            // hence returning `Ok(a)` is incorrect.
-            if !a.has_escaping_bound_vars() && !b.has_escaping_bound_vars() {
-                return Ok(a);
-            }
+            return Ok(a);
         }
 
         match (a.kind(), b.kind()) {
@@ -726,47 +717,6 @@ where
     }
 }
 
-/// When we encounter a binder like `for<..> fn(..)`, we actually have
-/// to walk the `fn` value to find all the values bound by the `for`
-/// (these are not explicitly present in the ty representation right
-/// now). This visitor handles that: it descends the type, tracking
-/// binder depth, and finds late-bound regions targeting the
-/// `for<..`>. For each of those, it creates an entry in
-/// `bound_region_scope`.
-struct ScopeInstantiator<'me, 'tcx> {
-    next_region: &'me mut dyn FnMut(ty::BoundRegion) -> ty::Region<'tcx>,
-    // The debruijn index of the scope we are instantiating.
-    target_index: ty::DebruijnIndex,
-    bound_region_scope: &'me mut BoundRegionScope<'tcx>,
-}
-
-impl<'me, 'tcx> TypeVisitor<TyCtxt<'tcx>> for ScopeInstantiator<'me, 'tcx> {
-    fn visit_binder<T: TypeVisitable<TyCtxt<'tcx>>>(
-        &mut self,
-        t: &ty::Binder<'tcx, T>,
-    ) -> ControlFlow<Self::BreakTy> {
-        self.target_index.shift_in(1);
-        t.super_visit_with(self);
-        self.target_index.shift_out(1);
-
-        ControlFlow::Continue(())
-    }
-
-    fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
-        let ScopeInstantiator { bound_region_scope, next_region, .. } = self;
-
-        match *r {
-            ty::ReLateBound(debruijn, br) if debruijn == self.target_index => {
-                bound_region_scope.map.entry(br).or_insert_with(|| next_region(br));
-            }
-
-            _ => {}
-        }
-
-        ControlFlow::Continue(())
-    }
-}
-
 /// The "type generalizer" is used when handling inference variables.
 ///
 /// The basic strategy for handling a constraint like `?A <: B` is to
@@ -780,11 +730,6 @@ impl<'me, 'tcx> TypeVisitor<TyCtxt<'tcx>> for ScopeInstantiator<'me, 'tcx> {
 /// value of `A`. Finally, we relate `&'0 u32 <: &'x u32`, which
 /// establishes `'0: 'x` as a constraint.
 ///
-/// As a side-effect of this generalization procedure, we also replace
-/// all the bound regions that we have traversed with concrete values,
-/// so that the resulting generalized type is independent from the
-/// scopes.
-///
 /// [blog post]: https://is.gd/0hKvIr
 struct TypeGeneralizer<'me, 'tcx, D>
 where
@@ -798,8 +743,6 @@ where
     /// some other type. What will be the variance at this point?
     ambient_variance: ty::Variance,
 
-    first_free_index: ty::DebruijnIndex,
-
     /// The vid of the type variable that is in the process of being
     /// instantiated. If we find this within the value we are folding,
     /// that means we would have created a cyclic value.
@@ -939,7 +882,7 @@ where
     ) -> RelateResult<'tcx, ty::Region<'tcx>> {
         debug!("TypeGeneralizer::regions(a={:?})", a);
 
-        if let ty::ReLateBound(debruijn, _) = *a && debruijn < self.first_free_index {
+        if let ty::ReLateBound(..) = *a {
             return Ok(a);
         }
 
@@ -958,7 +901,6 @@ where
         // FIXME(#54105) -- if the ambient variance is bivariant,
         // though, we may however need to check well-formedness or
         // risk a problem like #41677 again.
-
         let replacement_region_vid = self.delegate.generalize_existential(self.universe);
 
         Ok(replacement_region_vid)
@@ -1002,10 +944,7 @@ where
         T: Relate<'tcx>,
     {
         debug!("TypeGeneralizer::binders(a={:?})", a);
-
-        self.first_free_index.shift_in(1);
         let result = self.relate(a.skip_binder(), a.skip_binder())?;
-        self.first_free_index.shift_out(1);
         Ok(a.rebind(result))
     }
 }
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 32f9e883fd6bb..82c66b9dfb9f6 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -108,11 +108,7 @@ impl<'a, 'tcx> Encoder for EncodeContext<'a, 'tcx> {
         emit_i64(i64);
         emit_i32(i32);
         emit_i16(i16);
-        emit_i8(i8);
 
-        emit_bool(bool);
-        emit_char(char);
-        emit_str(&str);
         emit_raw_bytes(&[u8]);
     }
 }
diff --git a/compiler/rustc_middle/src/query/on_disk_cache.rs b/compiler/rustc_middle/src/query/on_disk_cache.rs
index e56faff5ed47c..220118ae5ccb8 100644
--- a/compiler/rustc_middle/src/query/on_disk_cache.rs
+++ b/compiler/rustc_middle/src/query/on_disk_cache.rs
@@ -1026,11 +1026,7 @@ impl<'a, 'tcx> Encoder for CacheEncoder<'a, 'tcx> {
         emit_i64(i64);
         emit_i32(i32);
         emit_i16(i16);
-        emit_i8(i8);
 
-        emit_bool(bool);
-        emit_char(char);
-        emit_str(&str);
         emit_raw_bytes(&[u8]);
     }
 }
diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs
index 7536903ef96fc..7fc75674da537 100644
--- a/compiler/rustc_middle/src/ty/codec.rs
+++ b/compiler/rustc_middle/src/ty/codec.rs
@@ -506,23 +506,18 @@ macro_rules! implement_ty_decoder {
 
             impl<$($typaram ),*> Decoder for $DecoderName<$($typaram),*> {
                 $crate::__impl_decoder_methods! {
+                    read_usize -> usize;
                     read_u128 -> u128;
                     read_u64 -> u64;
                     read_u32 -> u32;
                     read_u16 -> u16;
                     read_u8 -> u8;
-                    read_usize -> usize;
 
+                    read_isize -> isize;
                     read_i128 -> i128;
                     read_i64 -> i64;
                     read_i32 -> i32;
                     read_i16 -> i16;
-                    read_i8 -> i8;
-                    read_isize -> isize;
-
-                    read_bool -> bool;
-                    read_char -> char;
-                    read_str -> &str;
                 }
 
                 #[inline]
@@ -531,13 +526,13 @@ macro_rules! implement_ty_decoder {
                 }
 
                 #[inline]
-                fn position(&self) -> usize {
-                    self.opaque.position()
+                fn peek_byte(&self) -> u8 {
+                    self.opaque.peek_byte()
                 }
 
                 #[inline]
-                fn peek_byte(&self) -> u8 {
-                    self.opaque.peek_byte()
+                fn position(&self) -> usize {
+                    self.opaque.position()
                 }
             }
         }
diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs
index b3a3a25ebe863..7f995c69a4879 100644
--- a/compiler/rustc_mir_transform/src/const_prop.rs
+++ b/compiler/rustc_mir_transform/src/const_prop.rs
@@ -714,13 +714,22 @@ impl CanConstProp {
     }
 }
 
-impl Visitor<'_> for CanConstProp {
+impl<'tcx> Visitor<'tcx> for CanConstProp {
+    fn visit_place(&mut self, place: &Place<'tcx>, mut context: PlaceContext, loc: Location) {
+        use rustc_middle::mir::visit::PlaceContext::*;
+
+        // Dereferencing just read the addess of `place.local`.
+        if place.projection.first() == Some(&PlaceElem::Deref) {
+            context = NonMutatingUse(NonMutatingUseContext::Copy);
+        }
+
+        self.visit_local(place.local, context, loc);
+        self.visit_projection(place.as_ref(), context, loc);
+    }
+
     fn visit_local(&mut self, local: Local, context: PlaceContext, _: Location) {
         use rustc_middle::mir::visit::PlaceContext::*;
         match context {
-            // Projections are fine, because `&mut foo.x` will be caught by
-            // `MutatingUseContext::Borrow` elsewhere.
-            MutatingUse(MutatingUseContext::Projection)
             // These are just stores, where the storing is not propagatable, but there may be later
             // mutations of the same local via `Store`
             | MutatingUse(MutatingUseContext::Call)
@@ -751,7 +760,6 @@ impl Visitor<'_> for CanConstProp {
             NonMutatingUse(NonMutatingUseContext::Copy)
             | NonMutatingUse(NonMutatingUseContext::Move)
             | NonMutatingUse(NonMutatingUseContext::Inspect)
-            | NonMutatingUse(NonMutatingUseContext::Projection)
             | NonMutatingUse(NonMutatingUseContext::PlaceMention)
             | NonUse(_) => {}
 
@@ -771,6 +779,8 @@ impl Visitor<'_> for CanConstProp {
                 trace!("local {:?} can't be propagated because it's used: {:?}", local, context);
                 self.can_const_prop[local] = ConstPropMode::NoPropagation;
             }
+            MutatingUse(MutatingUseContext::Projection)
+            | NonMutatingUse(NonMutatingUseContext::Projection) => bug!("visit_place should not pass {context:?} for {local:?}"),
         }
     }
 }
diff --git a/compiler/rustc_serialize/src/opaque.rs b/compiler/rustc_serialize/src/opaque.rs
index a2ec318df6d83..6b559cb5b2f64 100644
--- a/compiler/rustc_serialize/src/opaque.rs
+++ b/compiler/rustc_serialize/src/opaque.rs
@@ -265,52 +265,41 @@ impl Drop for FileEncoder {
     }
 }
 
-macro_rules! file_encoder_write_leb128 {
-    ($enc:expr, $value:expr, $int_ty:ty, $fun:ident) => {{
-        const MAX_ENCODED_LEN: usize = $crate::leb128::max_leb128_len::<$int_ty>();
+macro_rules! write_leb128 {
+    ($this_fn:ident, $int_ty:ty, $write_leb_fn:ident) => {
+        #[inline]
+        fn $this_fn(&mut self, v: $int_ty) {
+            const MAX_ENCODED_LEN: usize = $crate::leb128::max_leb128_len::<$int_ty>();
 
-        // We ensure this during `FileEncoder` construction.
-        debug_assert!($enc.capacity() >= MAX_ENCODED_LEN);
+            // We ensure this during `FileEncoder` construction.
+            debug_assert!(self.capacity() >= MAX_ENCODED_LEN);
 
-        let mut buffered = $enc.buffered;
+            let mut buffered = self.buffered;
 
-        // This can't overflow. See assertion in `FileEncoder::with_capacity`.
-        if std::intrinsics::unlikely(buffered + MAX_ENCODED_LEN > $enc.capacity()) {
-            $enc.flush();
-            buffered = 0;
-        }
+            // This can't overflow. See assertion in `FileEncoder::with_capacity`.
+            if std::intrinsics::unlikely(buffered + MAX_ENCODED_LEN > self.capacity()) {
+                self.flush();
+                buffered = 0;
+            }
 
-        // SAFETY: The above check and flush ensures that there is enough
-        // room to write the encoded value to the buffer.
-        let buf = unsafe {
-            &mut *($enc.buf.as_mut_ptr().add(buffered) as *mut [MaybeUninit<u8>; MAX_ENCODED_LEN])
-        };
+            // SAFETY: The above check and flush ensures that there is enough
+            // room to write the encoded value to the buffer.
+            let buf = unsafe {
+                &mut *(self.buf.as_mut_ptr().add(buffered)
+                    as *mut [MaybeUninit<u8>; MAX_ENCODED_LEN])
+            };
 
-        let encoded = leb128::$fun(buf, $value);
-        $enc.buffered = buffered + encoded.len();
-    }};
+            let encoded = leb128::$write_leb_fn(buf, v);
+            self.buffered = buffered + encoded.len();
+        }
+    };
 }
 
 impl Encoder for FileEncoder {
-    #[inline]
-    fn emit_usize(&mut self, v: usize) {
-        file_encoder_write_leb128!(self, v, usize, write_usize_leb128)
-    }
-
-    #[inline]
-    fn emit_u128(&mut self, v: u128) {
-        file_encoder_write_leb128!(self, v, u128, write_u128_leb128)
-    }
-
-    #[inline]
-    fn emit_u64(&mut self, v: u64) {
-        file_encoder_write_leb128!(self, v, u64, write_u64_leb128)
-    }
-
-    #[inline]
-    fn emit_u32(&mut self, v: u32) {
-        file_encoder_write_leb128!(self, v, u32, write_u32_leb128)
-    }
+    write_leb128!(emit_usize, usize, write_usize_leb128);
+    write_leb128!(emit_u128, u128, write_u128_leb128);
+    write_leb128!(emit_u64, u64, write_u64_leb128);
+    write_leb128!(emit_u32, u32, write_u32_leb128);
 
     #[inline]
     fn emit_u16(&mut self, v: u16) {
@@ -322,25 +311,10 @@ impl Encoder for FileEncoder {
         self.write_one(v);
     }
 
-    #[inline]
-    fn emit_isize(&mut self, v: isize) {
-        file_encoder_write_leb128!(self, v, isize, write_isize_leb128)
-    }
-
-    #[inline]
-    fn emit_i128(&mut self, v: i128) {
-        file_encoder_write_leb128!(self, v, i128, write_i128_leb128)
-    }
-
-    #[inline]
-    fn emit_i64(&mut self, v: i64) {
-        file_encoder_write_leb128!(self, v, i64, write_i64_leb128)
-    }
-
-    #[inline]
-    fn emit_i32(&mut self, v: i32) {
-        file_encoder_write_leb128!(self, v, i32, write_i32_leb128)
-    }
+    write_leb128!(emit_isize, isize, write_isize_leb128);
+    write_leb128!(emit_i128, i128, write_i128_leb128);
+    write_leb128!(emit_i64, i64, write_i64_leb128);
+    write_leb128!(emit_i32, i32, write_i32_leb128);
 
     #[inline]
     fn emit_i16(&mut self, v: i16) {
@@ -437,30 +411,19 @@ impl<'a> MemDecoder<'a> {
 }
 
 macro_rules! read_leb128 {
-    ($dec:expr, $fun:ident) => {{ leb128::$fun($dec) }};
+    ($this_fn:ident, $int_ty:ty, $read_leb_fn:ident) => {
+        #[inline]
+        fn $this_fn(&mut self) -> $int_ty {
+            leb128::$read_leb_fn(self)
+        }
+    };
 }
 
 impl<'a> Decoder for MemDecoder<'a> {
-    #[inline]
-    fn position(&self) -> usize {
-        // SAFETY: This type guarantees start <= current
-        unsafe { self.current.sub_ptr(self.start) }
-    }
-
-    #[inline]
-    fn read_u128(&mut self) -> u128 {
-        read_leb128!(self, read_u128_leb128)
-    }
-
-    #[inline]
-    fn read_u64(&mut self) -> u64 {
-        read_leb128!(self, read_u64_leb128)
-    }
-
-    #[inline]
-    fn read_u32(&mut self) -> u32 {
-        read_leb128!(self, read_u32_leb128)
-    }
+    read_leb128!(read_usize, usize, read_usize_leb128);
+    read_leb128!(read_u128, u128, read_u128_leb128);
+    read_leb128!(read_u64, u64, read_u64_leb128);
+    read_leb128!(read_u32, u32, read_u32_leb128);
 
     #[inline]
     fn read_u16(&mut self) -> u16 {
@@ -480,36 +443,16 @@ impl<'a> Decoder for MemDecoder<'a> {
         }
     }
 
-    #[inline]
-    fn read_usize(&mut self) -> usize {
-        read_leb128!(self, read_usize_leb128)
-    }
-
-    #[inline]
-    fn read_i128(&mut self) -> i128 {
-        read_leb128!(self, read_i128_leb128)
-    }
-
-    #[inline]
-    fn read_i64(&mut self) -> i64 {
-        read_leb128!(self, read_i64_leb128)
-    }
-
-    #[inline]
-    fn read_i32(&mut self) -> i32 {
-        read_leb128!(self, read_i32_leb128)
-    }
+    read_leb128!(read_isize, isize, read_isize_leb128);
+    read_leb128!(read_i128, i128, read_i128_leb128);
+    read_leb128!(read_i64, i64, read_i64_leb128);
+    read_leb128!(read_i32, i32, read_i32_leb128);
 
     #[inline]
     fn read_i16(&mut self) -> i16 {
         i16::from_le_bytes(self.read_array())
     }
 
-    #[inline]
-    fn read_isize(&mut self) -> isize {
-        read_leb128!(self, read_isize_leb128)
-    }
-
     #[inline]
     fn read_raw_bytes(&mut self, bytes: usize) -> &'a [u8] {
         if bytes > self.remaining() {
@@ -532,6 +475,12 @@ impl<'a> Decoder for MemDecoder<'a> {
         // Since we just checked current == end, the current pointer must be inbounds.
         unsafe { *self.current }
     }
+
+    #[inline]
+    fn position(&self) -> usize {
+        // SAFETY: This type guarantees start <= current
+        unsafe { self.current.sub_ptr(self.start) }
+    }
 }
 
 // Specializations for contiguous byte sequences follow. The default implementations for slices
diff --git a/compiler/rustc_serialize/src/serialize.rs b/compiler/rustc_serialize/src/serialize.rs
index e1bc598736fee..06166cabc1872 100644
--- a/compiler/rustc_serialize/src/serialize.rs
+++ b/compiler/rustc_serialize/src/serialize.rs
@@ -1,9 +1,5 @@
 //! Support code for encoding and decoding types.
 
-/*
-Core encoding and decoding interfaces.
-*/
-
 use std::alloc::Allocator;
 use std::borrow::Cow;
 use std::cell::{Cell, RefCell};
@@ -35,13 +31,13 @@ const STR_SENTINEL: u8 = 0xC1;
 /// really makes sense to store floating-point values at all.
 /// (If you need it, revert <https://github.com/rust-lang/rust/pull/109984>.)
 pub trait Encoder {
-    // Primitive types:
     fn emit_usize(&mut self, v: usize);
     fn emit_u128(&mut self, v: u128);
     fn emit_u64(&mut self, v: u64);
     fn emit_u32(&mut self, v: u32);
     fn emit_u16(&mut self, v: u16);
     fn emit_u8(&mut self, v: u8);
+
     fn emit_isize(&mut self, v: isize);
     fn emit_i128(&mut self, v: i128);
     fn emit_i64(&mut self, v: i64);
@@ -93,13 +89,13 @@ pub trait Encoder {
 /// really makes sense to store floating-point values at all.
 /// (If you need it, revert <https://github.com/rust-lang/rust/pull/109984>.)
 pub trait Decoder {
-    // Primitive types:
     fn read_usize(&mut self) -> usize;
     fn read_u128(&mut self) -> u128;
     fn read_u64(&mut self) -> u64;
     fn read_u32(&mut self) -> u32;
     fn read_u16(&mut self) -> u16;
     fn read_u8(&mut self) -> u8;
+
     fn read_isize(&mut self) -> isize;
     fn read_i128(&mut self) -> i128;
     fn read_i64(&mut self) -> i64;
diff --git a/library/core/src/tuple.rs b/library/core/src/tuple.rs
index c46c49547f6d4..2a8403c85a4eb 100644
--- a/library/core/src/tuple.rs
+++ b/library/core/src/tuple.rs
@@ -101,7 +101,7 @@ macro_rules! tuple_impls {
             }
         }
 
-        #[stable(feature = "array_tuple_conv", since = "1.63.0")]
+        #[stable(feature = "array_tuple_conv", since = "CURRENT_RUSTC_VERSION")]
         impl<T> From<[T; ${count(T)}]> for ($(${ignore(T)} T,)+) {
             #[inline]
             #[allow(non_snake_case)]
@@ -111,7 +111,7 @@ macro_rules! tuple_impls {
             }
         }
 
-        #[stable(feature = "array_tuple_conv", since = "1.63.0")]
+        #[stable(feature = "array_tuple_conv", since = "CURRENT_RUSTC_VERSION")]
         impl<T> From<($(${ignore(T)} T,)+)> for [T; ${count(T)}] {
             #[inline]
             #[allow(non_snake_case)]
diff --git a/library/std/src/sys/common/thread_local/mod.rs b/library/std/src/sys/common/thread_local/mod.rs
index 951d509ec9533..77f645883102c 100644
--- a/library/std/src/sys/common/thread_local/mod.rs
+++ b/library/std/src/sys/common/thread_local/mod.rs
@@ -1,5 +1,10 @@
 #![unstable(feature = "thread_local_internals", reason = "should not be necessary", issue = "none")]
 
+// There are three thread-local implementations: "static", "fast", "OS".
+// The "OS" thread local key type is accessed via platform-specific API calls and is slow, while the
+// "fast" key type is accessed via code generated via LLVM, where TLS keys are set up by the linker.
+// "static" is for single-threaded platforms where a global static is sufficient.
+
 cfg_if::cfg_if! {
     if #[cfg(all(target_family = "wasm", not(target_feature = "atomics")))] {
         #[doc(hidden)]
diff --git a/library/std/src/sys/common/thread_local/os_local.rs b/library/std/src/sys/common/thread_local/os_local.rs
index d004897df281a..5d48ce1e03bc3 100644
--- a/library/std/src/sys/common/thread_local/os_local.rs
+++ b/library/std/src/sys/common/thread_local/os_local.rs
@@ -18,7 +18,7 @@ pub macro thread_local_inner {
         ) -> $crate::option::Option<&'static $t> {
             const INIT_EXPR: $t = $init;
 
-                        // On platforms without `#[thread_local]` we fall back to the
+            // On platforms without `#[thread_local]` we fall back to the
             // same implementation as below for os thread locals.
             #[inline]
             const fn __init() -> $t { INIT_EXPR }
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index 9cdc17a287c96..f712c872708ac 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -193,22 +193,22 @@ pub use scoped::{scope, Scope, ScopedJoinHandle};
 #[macro_use]
 mod local;
 
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use self::local::{AccessError, LocalKey};
-
-// Provide the type used by the thread_local! macro to access TLS keys. This
-// needs to be kept in sync with the macro itself (in `local.rs`).
-// There are three types: "static", "fast", "OS". The "OS" thread local key
-// type is accessed via platform-specific API calls and is slow, while the "fast"
-// key type is accessed via code generated via LLVM, where TLS keys are set up
-// by the elf linker. "static" is for single-threaded platforms where a global
-// static is sufficient.
-
-// Implementation details used by the thread_local!{} macro.
-#[doc(hidden)]
-#[unstable(feature = "thread_local_internals", issue = "none")]
-pub mod local_impl {
-    pub use crate::sys::common::thread_local::{thread_local_inner, Key};
+cfg_if::cfg_if! {
+    if #[cfg(test)] {
+        // Avoid duplicating the global state assoicated with thread-locals between this crate and
+        // realstd. Miri relies on this.
+        pub use realstd::thread::{local_impl, AccessError, LocalKey};
+    } else {
+        #[stable(feature = "rust1", since = "1.0.0")]
+        pub use self::local::{AccessError, LocalKey};
+
+        // Implementation details used by the thread_local!{} macro.
+        #[doc(hidden)]
+        #[unstable(feature = "thread_local_internals", issue = "none")]
+        pub mod local_impl {
+            pub use crate::sys::common::thread_local::{thread_local_inner, Key};
+        }
+    }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 4ef95b3370ff8..ac51dc51aeb02 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -1442,6 +1442,28 @@ impl Config {
         git
     }
 
+    pub(crate) fn test_args(&self) -> Vec<&str> {
+        let mut test_args = match self.cmd {
+            Subcommand::Test { ref test_args, .. } | Subcommand::Bench { ref test_args, .. } => {
+                test_args.iter().flat_map(|s| s.split_whitespace()).collect()
+            }
+            _ => vec![],
+        };
+        test_args.extend(self.free_args.iter().map(|s| s.as_str()));
+        test_args
+    }
+
+    pub(crate) fn args(&self) -> Vec<&str> {
+        let mut args = match self.cmd {
+            Subcommand::Run { ref args, .. } => {
+                args.iter().flat_map(|s| s.split_whitespace()).collect()
+            }
+            _ => vec![],
+        };
+        args.extend(self.free_args.iter().map(|s| s.as_str()));
+        args
+    }
+
     /// Bootstrap embeds a version number into the name of shared libraries it uploads in CI.
     /// Return the version it would have used for the given commit.
     pub(crate) fn artifact_version_part(&self, commit: &str) -> String {
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index ab7f7350d5f4d..9cead7adc8c35 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -822,6 +822,8 @@ fn copy_src_dirs(
             "llvm-project\\compiler-rt",
             "llvm-project/cmake",
             "llvm-project\\cmake",
+            "llvm-project/runtimes",
+            "llvm-project\\runtimes",
         ];
         if spath.contains("llvm-project")
             && !spath.ends_with("llvm-project")
diff --git a/src/bootstrap/flags.rs b/src/bootstrap/flags.rs
index b6f5f31039838..2a0ebee9a6b5b 100644
--- a/src/bootstrap/flags.rs
+++ b/src/bootstrap/flags.rs
@@ -745,15 +745,6 @@ impl Subcommand {
         }
     }
 
-    pub fn test_args(&self) -> Vec<&str> {
-        match *self {
-            Subcommand::Test { ref test_args, .. } | Subcommand::Bench { ref test_args, .. } => {
-                test_args.iter().flat_map(|s| s.split_whitespace()).collect()
-            }
-            _ => vec![],
-        }
-    }
-
     pub fn rustc_args(&self) -> Vec<&str> {
         match *self {
             Subcommand::Test { ref rustc_args, .. } => {
@@ -763,15 +754,6 @@ impl Subcommand {
         }
     }
 
-    pub fn args(&self) -> Vec<&str> {
-        match *self {
-            Subcommand::Run { ref args, .. } => {
-                args.iter().flat_map(|s| s.split_whitespace()).collect()
-            }
-            _ => vec![],
-        }
-    }
-
     pub fn fail_fast(&self) -> bool {
         match *self {
             Subcommand::Test { fail_fast, .. } => fail_fast,
diff --git a/src/bootstrap/run.rs b/src/bootstrap/run.rs
index e14440f57a8a6..cb15d9a6325b3 100644
--- a/src/bootstrap/run.rs
+++ b/src/bootstrap/run.rs
@@ -105,7 +105,7 @@ impl Step for BumpStage0 {
 
     fn run(self, builder: &Builder<'_>) -> Self::Output {
         let mut cmd = builder.tool_cmd(Tool::BumpStage0);
-        cmd.args(builder.config.cmd.args());
+        cmd.args(builder.config.args());
         builder.run(&mut cmd);
     }
 }
@@ -182,8 +182,7 @@ impl Step for Miri {
         miri.add_rustc_lib_path(builder, compiler);
         // Forward arguments.
         miri.arg("--").arg("--target").arg(target.rustc_target_arg());
-        miri.args(builder.config.cmd.args());
-        miri.args(&builder.config.free_args);
+        miri.args(builder.config.args());
 
         // miri tests need to know about the stage sysroot
         miri.env("MIRI_SYSROOT", &miri_sysroot);
diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index cfccb51662785..28813266a4d9e 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -263,7 +263,7 @@ impl Step for Cargotest {
             builder,
             cmd.arg(&cargo)
                 .arg(&out_dir)
-                .args(builder.config.cmd.test_args())
+                .args(builder.config.test_args())
                 .env("RUSTC", builder.rustc(compiler))
                 .env("RUSTDOC", builder.rustdoc(compiler)),
         );
@@ -634,7 +634,7 @@ impl Step for Miri {
             .arg(builder.src.join("src/tools/miri/test-cargo-miri/Cargo.toml"));
         cargo.arg("--target").arg(target.rustc_target_arg());
         cargo.arg("--tests"); // don't run doctests, they are too confused by the staging
-        cargo.arg("--").args(builder.config.cmd.test_args());
+        cargo.arg("--").args(builder.config.test_args());
 
         // Tell `cargo miri` where to find things.
         cargo.env("MIRI_SYSROOT", &miri_sysroot);
@@ -1060,7 +1060,7 @@ impl Step for RustdocGUI {
                 }
             }
         }
-        for test_arg in builder.config.cmd.test_args() {
+        for test_arg in builder.config.test_args() {
             command.arg(test_arg);
         }
         builder.run(&mut command);
@@ -1555,8 +1555,7 @@ note: if you're sure you want to do this, please open an issue as to why. In the
             .filter_map(|p| util::is_valid_test_suite_arg(p, suite_path, builder))
             .collect();
 
-        test_args.append(&mut builder.config.cmd.test_args());
-        test_args.extend(builder.config.free_args.iter().map(|s| s.as_str()));
+        test_args.append(&mut builder.config.test_args());
 
         // On Windows, replace forward slashes in test-args by backslashes
         // so the correct filters are passed to libtest
@@ -1962,7 +1961,7 @@ fn markdown_test(builder: &Builder<'_>, compiler: Compiler, markdown: &Path) ->
     cmd.arg(markdown);
     cmd.env("RUSTC_BOOTSTRAP", "1");
 
-    let test_args = builder.config.cmd.test_args().join(" ");
+    let test_args = builder.config.test_args().join(" ");
     cmd.arg("--test-args").arg(test_args);
 
     if builder.config.verbose_tests {
@@ -2099,7 +2098,7 @@ fn prepare_cargo_test(
         cargo.arg("-p").arg(krate);
     }
 
-    cargo.arg("--").args(&builder.config.cmd.test_args()).args(libtest_args);
+    cargo.arg("--").args(&builder.config.test_args()).args(libtest_args);
     if !builder.config.verbose_tests {
         cargo.arg("--quiet");
     }
diff --git a/tests/mir-opt/const_prop/address_of_pair.fn0.ConstProp.diff b/tests/mir-opt/const_prop/address_of_pair.fn0.ConstProp.diff
new file mode 100644
index 0000000000000..d50b12044ceb2
--- /dev/null
+++ b/tests/mir-opt/const_prop/address_of_pair.fn0.ConstProp.diff
@@ -0,0 +1,46 @@
+- // MIR for `fn0` before ConstProp
++ // MIR for `fn0` after ConstProp
+  
+  fn fn0() -> bool {
+      let mut _0: bool;                    // return place in scope 0 at $DIR/address_of_pair.rs:+0:17: +0:21
+      let mut _1: !;                       // in scope 0 at $DIR/address_of_pair.rs:+0:22: +9:2
+      let mut _2: (i32, bool);             // in scope 0 at $DIR/address_of_pair.rs:+1:9: +1:17
+      let _4: ();                          // in scope 0 at $DIR/address_of_pair.rs:+4:5: +6:6
+      let mut _6: bool;                    // in scope 0 at $DIR/address_of_pair.rs:+7:16: +7:22
+      scope 1 {
+          debug pair => _2;                // in scope 1 at $DIR/address_of_pair.rs:+1:9: +1:17
+          let _3: *mut bool;               // in scope 1 at $DIR/address_of_pair.rs:+2:9: +2:12
+          scope 2 {
+              debug ptr => _3;             // in scope 2 at $DIR/address_of_pair.rs:+2:9: +2:12
+              let _5: bool;                // in scope 2 at $DIR/address_of_pair.rs:+7:9: +7:12
+              scope 3 {
+              }
+              scope 4 {
+                  debug ret => _5;         // in scope 4 at $DIR/address_of_pair.rs:+7:9: +7:12
+              }
+          }
+      }
+  
+      bb0: {
+          StorageLive(_2);                 // scope 0 at $DIR/address_of_pair.rs:+1:9: +1:17
+          _2 = (const 1_i32, const false); // scope 0 at $DIR/address_of_pair.rs:+1:20: +1:30
+          StorageLive(_3);                 // scope 1 at $DIR/address_of_pair.rs:+2:9: +2:12
+          _3 = &raw mut (_2.1: bool);      // scope 1 at $SRC_DIR/core/src/ptr/mod.rs:LL:COL
+          _2 = (const 1_i32, const false); // scope 2 at $DIR/address_of_pair.rs:+3:5: +3:22
+          StorageLive(_4);                 // scope 2 at $DIR/address_of_pair.rs:+4:5: +6:6
+          (*_3) = const true;              // scope 3 at $DIR/address_of_pair.rs:+5:9: +5:20
+          _4 = const ();                   // scope 3 at $DIR/address_of_pair.rs:+4:5: +6:6
+          StorageDead(_4);                 // scope 2 at $DIR/address_of_pair.rs:+6:5: +6:6
+          StorageLive(_5);                 // scope 2 at $DIR/address_of_pair.rs:+7:9: +7:12
+          StorageLive(_6);                 // scope 2 at $DIR/address_of_pair.rs:+7:16: +7:22
+          _6 = (_2.1: bool);               // scope 2 at $DIR/address_of_pair.rs:+7:16: +7:22
+          _5 = Not(move _6);               // scope 2 at $DIR/address_of_pair.rs:+7:15: +7:22
+          StorageDead(_6);                 // scope 2 at $DIR/address_of_pair.rs:+7:21: +7:22
+          _0 = _5;                         // scope 4 at $DIR/address_of_pair.rs:+8:12: +8:15
+          StorageDead(_5);                 // scope 2 at $DIR/address_of_pair.rs:+9:1: +9:2
+          StorageDead(_3);                 // scope 1 at $DIR/address_of_pair.rs:+9:1: +9:2
+          StorageDead(_2);                 // scope 0 at $DIR/address_of_pair.rs:+9:1: +9:2
+          return;                          // scope 0 at $DIR/address_of_pair.rs:+9:2: +9:2
+      }
+  }
+  
diff --git a/tests/mir-opt/const_prop/address_of_pair.rs b/tests/mir-opt/const_prop/address_of_pair.rs
new file mode 100644
index 0000000000000..43dc9bae62534
--- /dev/null
+++ b/tests/mir-opt/const_prop/address_of_pair.rs
@@ -0,0 +1,17 @@
+// unit-test: ConstProp
+
+// EMIT_MIR address_of_pair.fn0.ConstProp.diff
+pub fn fn0() -> bool {
+    let mut pair = (1, false);
+    let ptr = core::ptr::addr_of_mut!(pair.1);
+    pair = (1, false);
+    unsafe {
+        *ptr = true;
+    }
+    let ret = !pair.1;
+    return ret;
+}
+
+pub fn main() {
+    println!("{}", fn0());
+}
diff --git a/tests/mir-opt/const_prop_miscompile.bar.ConstProp.diff b/tests/mir-opt/const_prop_miscompile.bar.ConstProp.diff
index def9fc6428fb6..a5f52d08957c8 100644
--- a/tests/mir-opt/const_prop_miscompile.bar.ConstProp.diff
+++ b/tests/mir-opt/const_prop_miscompile.bar.ConstProp.diff
@@ -19,8 +19,7 @@
   
       bb0: {
           StorageLive(_1);                 // scope 0 at $DIR/const_prop_miscompile.rs:+1:9: +1:14
--         _1 = (const 1_i32,);             // scope 0 at $DIR/const_prop_miscompile.rs:+1:17: +1:21
-+         _1 = const (1_i32,);             // scope 0 at $DIR/const_prop_miscompile.rs:+1:17: +1:21
+          _1 = (const 1_i32,);             // scope 0 at $DIR/const_prop_miscompile.rs:+1:17: +1:21
           StorageLive(_2);                 // scope 1 at $DIR/const_prop_miscompile.rs:+2:5: +4:6
           StorageLive(_3);                 // scope 2 at $DIR/const_prop_miscompile.rs:+3:10: +3:22
           _3 = &raw mut (_1.0: i32);       // scope 2 at $DIR/const_prop_miscompile.rs:+3:10: +3:22
diff --git a/tests/mir-opt/const_prop_miscompile.foo.ConstProp.diff b/tests/mir-opt/const_prop_miscompile.foo.ConstProp.diff
index b54c10a140f2c..42ddc2a56208a 100644
--- a/tests/mir-opt/const_prop_miscompile.foo.ConstProp.diff
+++ b/tests/mir-opt/const_prop_miscompile.foo.ConstProp.diff
@@ -16,8 +16,7 @@
   
       bb0: {
           StorageLive(_1);                 // scope 0 at $DIR/const_prop_miscompile.rs:+1:9: +1:14
--         _1 = (const 1_i32,);             // scope 0 at $DIR/const_prop_miscompile.rs:+1:17: +1:21
-+         _1 = const (1_i32,);             // scope 0 at $DIR/const_prop_miscompile.rs:+1:17: +1:21
+          _1 = (const 1_i32,);             // scope 0 at $DIR/const_prop_miscompile.rs:+1:17: +1:21
           StorageLive(_2);                 // scope 1 at $DIR/const_prop_miscompile.rs:+2:6: +2:14
           _2 = &mut (_1.0: i32);           // scope 1 at $DIR/const_prop_miscompile.rs:+2:6: +2:14
           (*_2) = const 5_i32;             // scope 1 at $DIR/const_prop_miscompile.rs:+2:5: +2:18
diff --git a/tests/ui/impl-trait/issues/issue-86800.rs b/tests/ui/impl-trait/issues/issue-86800.rs
index 351243c6727da..ec4fda322d04f 100644
--- a/tests/ui/impl-trait/issues/issue-86800.rs
+++ b/tests/ui/impl-trait/issues/issue-86800.rs
@@ -1,14 +1,12 @@
 #![feature(type_alias_impl_trait)]
 
 // edition:2021
-// unset-rustc-env:RUST_BACKTRACE
 // compile-flags:-Z treat-err-as-bug=1
-// error-pattern:stack backtrace:
+// error-pattern: aborting due to `-Z treat-err-as-bug=1`
 // failure-status:101
-// normalize-stderr-test "note: .*" -> ""
-// normalize-stderr-test "thread 'rustc' .*" -> ""
-// normalize-stderr-test " +[0-9]+:.*\n" -> ""
-// normalize-stderr-test " +at .*\n" -> ""
+// normalize-stderr-test ".*note: .*\n\n" -> ""
+// normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
+// rustc-env:RUST_BACKTRACE=0
 
 use std::future::Future;
 
diff --git a/tests/ui/impl-trait/issues/issue-86800.stderr b/tests/ui/impl-trait/issues/issue-86800.stderr
index f3a773837785e..facab390d1524 100644
--- a/tests/ui/impl-trait/issues/issue-86800.stderr
+++ b/tests/ui/impl-trait/issues/issue-86800.stderr
@@ -1,24 +1,12 @@
 error: unconstrained opaque type
-  --> $DIR/issue-86800.rs:33:34
+  --> $DIR/issue-86800.rs:31:34
    |
 LL | type TransactionFuture<'__, O> = impl '__ + Future<Output = TransactionResult<O>>;
    |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = 
-
-
-stack backtrace:
-
 error: the compiler unexpectedly panicked. this is a bug.
 
-
-
-
-
-
-
 query stack during panic:
 #0 [type_of] computing type of `TransactionFuture::{opaque#0}`
 #1 [check_mod_item_types] checking item types in top-level module
-#2 [analysis] running analysis passes on this crate
 end of query stack
diff --git a/tests/ui/panics/default-backtrace-ice.rs b/tests/ui/panics/default-backtrace-ice.rs
index fd86a3f9dfaff..b40203c339d05 100644
--- a/tests/ui/panics/default-backtrace-ice.rs
+++ b/tests/ui/panics/default-backtrace-ice.rs
@@ -2,8 +2,20 @@
 // compile-flags:-Z treat-err-as-bug=1
 // error-pattern:stack backtrace:
 // failure-status:101
+// ignore-msvc
 // normalize-stderr-test "note: .*" -> ""
 // normalize-stderr-test "thread 'rustc' .*" -> ""
-// normalize-stderr-test "  .*\n" -> ""
+// normalize-stderr-test " +\d+:.*__rust_begin_short_backtrace.*" -> "(begin_short_backtrace)"
+// normalize-stderr-test " +\d+:.*__rust_end_short_backtrace.*" -> "(end_short_backtrace)"
+// normalize-stderr-test " +\d+:.*\n" -> ""
+// normalize-stderr-test " +at .*\n" -> ""
+//
+// This test makes sure that full backtraces are used for ICEs when
+// RUST_BACKTRACE is not set. It does this by checking for the presence of
+// `__rust_{begin,end}_short_backtrace` markers, which only appear in full
+// backtraces. The rest of the backtrace is filtered out.
+//
+// Ignored on msvc becaue the `__rust_{begin,end}_short_backtrace` symbols
+// aren't reliable.
 
 fn main() { missing_ident; }
diff --git a/tests/ui/panics/default-backtrace-ice.stderr b/tests/ui/panics/default-backtrace-ice.stderr
index 4bd4780e25f6b..ddbfc4e7f3a0c 100644
--- a/tests/ui/panics/default-backtrace-ice.stderr
+++ b/tests/ui/panics/default-backtrace-ice.stderr
@@ -1,8 +1,13 @@
 error[E0425]: cannot find value `missing_ident` in this scope
+  --> $DIR/default-backtrace-ice.rs:21:13
+   |
 LL | fn main() { missing_ident; }
+   |             ^^^^^^^^^^^^^ not found in this scope
 
 
 stack backtrace:
+(end_short_backtrace)
+(begin_short_backtrace)
 
 error: the compiler unexpectedly panicked. this is a bug.