diff --git a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
index df4cc295fac5f..80551518d3c5d 100644
--- a/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/fn_queries.rs
@@ -1,6 +1,5 @@
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_middle::hir::map::blocks::FnLikeNode;
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::symbol::Symbol;
@@ -44,8 +43,8 @@ fn is_const_fn_raw(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
         } else {
             false
         }
-    } else if let Some(fn_like) = FnLikeNode::from_node(node) {
-        if fn_like.constness() == hir::Constness::Const {
+    } else if let Some(fn_kind) = node.fn_kind() {
+        if fn_kind.constness() == hir::Constness::Const {
             return true;
         }
 
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index b5c1e31c258ef..6f25715fbecc4 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -1,6 +1,7 @@
 use crate::def::{CtorKind, DefKind, Res};
 use crate::def_id::DefId;
 crate use crate::hir_id::{HirId, ItemLocalId};
+use crate::intravisit::FnKind;
 use crate::LangItem;
 
 use rustc_ast::util::parser::ExprPrecedence;
@@ -3258,6 +3259,32 @@ impl<'hir> Node<'hir> {
             _ => None,
         }
     }
+
+    pub fn fn_kind(self) -> Option<FnKind<'hir>> {
+        match self {
+            Node::Item(i) => match i.kind {
+                ItemKind::Fn(ref sig, ref generics, _) => {
+                    Some(FnKind::ItemFn(i.ident, generics, sig.header, &i.vis))
+                }
+                _ => None,
+            },
+            Node::TraitItem(ti) => match ti.kind {
+                TraitItemKind::Fn(ref sig, TraitFn::Provided(_)) => {
+                    Some(FnKind::Method(ti.ident, sig, None))
+                }
+                _ => None,
+            },
+            Node::ImplItem(ii) => match ii.kind {
+                ImplItemKind::Fn(ref sig, _) => Some(FnKind::Method(ii.ident, sig, Some(&ii.vis))),
+                _ => None,
+            },
+            Node::Expr(e) => match e.kind {
+                ExprKind::Closure(..) => Some(FnKind::Closure),
+                _ => None,
+            },
+            _ => None,
+        }
+    }
 }
 
 // Some nodes are used a lot. Make sure they don't unintentionally get bigger.
diff --git a/compiler/rustc_hir/src/intravisit.rs b/compiler/rustc_hir/src/intravisit.rs
index 3e58af1f167aa..cff543760f42a 100644
--- a/compiler/rustc_hir/src/intravisit.rs
+++ b/compiler/rustc_hir/src/intravisit.rs
@@ -117,6 +117,14 @@ impl<'a> FnKind<'a> {
             FnKind::Closure => None,
         }
     }
+
+    pub fn constness(self) -> Constness {
+        self.header().map_or(Constness::NotConst, |header| header.constness)
+    }
+
+    pub fn asyncness(self) -> IsAsync {
+        self.header().map_or(IsAsync::NotAsync, |header| header.asyncness)
+    }
 }
 
 /// An abstract representation of the HIR `rustc_middle::hir::map::Map`.
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs
index 8dcdd4b149ea6..90bc5b3b2fed1 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs
@@ -143,9 +143,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         // similar to the asyncness fn in rustc_ty_utils::ty
         let hir_id = self.tcx().hir().local_def_id_to_hir_id(local_def_id);
         let node = self.tcx().hir().get(hir_id);
-        let fn_like = rustc_middle::hir::map::blocks::FnLikeNode::from_node(node)?;
-
-        Some(fn_like.asyncness())
+        let fn_kind = node.fn_kind()?;
+        Some(fn_kind.asyncness())
     }
 
     // Here, we check for the case where the anonymous region
diff --git a/compiler/rustc_middle/src/hir/map/blocks.rs b/compiler/rustc_middle/src/hir/map/blocks.rs
deleted file mode 100644
index 8efec8ef5674d..0000000000000
--- a/compiler/rustc_middle/src/hir/map/blocks.rs
+++ /dev/null
@@ -1,239 +0,0 @@
-//! This module provides a simplified abstraction for working with
-//! code blocks identified by their integer `NodeId`. In particular,
-//! it captures a common set of attributes that all "function-like
-//! things" (represented by `FnLike` instances) share. For example,
-//! all `FnLike` instances have a type signature (be it explicit or
-//! inferred). And all `FnLike` instances have a body, i.e., the code
-//! that is run when the function-like thing it represents is invoked.
-//!
-//! With the above abstraction in place, one can treat the program
-//! text as a collection of blocks of code (and most such blocks are
-//! nested within a uniquely determined `FnLike`), and users can ask
-//! for the `Code` associated with a particular NodeId.
-
-use crate::hir::map::Map;
-use rustc_hir as hir;
-use rustc_hir::intravisit::FnKind;
-use rustc_hir::{Expr, FnDecl, Node};
-use rustc_span::symbol::Ident;
-use rustc_span::Span;
-
-/// An FnLikeNode is a Node that is like a fn, in that it has a decl
-/// and a body (as well as a NodeId, a span, etc).
-///
-/// More specifically, it is one of either:
-///
-///   - A function item,
-///   - A closure expr (i.e., an ExprKind::Closure), or
-///   - The default implementation for a trait method.
-///
-/// To construct one, use the `Code::from_node` function.
-#[derive(Copy, Clone, Debug)]
-pub struct FnLikeNode<'a> {
-    node: Node<'a>,
-}
-
-/// MaybeFnLike wraps a method that indicates if an object
-/// corresponds to some FnLikeNode.
-trait MaybeFnLike {
-    fn is_fn_like(&self) -> bool;
-}
-
-impl MaybeFnLike for hir::Item<'_> {
-    fn is_fn_like(&self) -> bool {
-        matches!(self.kind, hir::ItemKind::Fn(..))
-    }
-}
-
-impl MaybeFnLike for hir::ImplItem<'_> {
-    fn is_fn_like(&self) -> bool {
-        matches!(self.kind, hir::ImplItemKind::Fn(..))
-    }
-}
-
-impl MaybeFnLike for hir::TraitItem<'_> {
-    fn is_fn_like(&self) -> bool {
-        matches!(self.kind, hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(_)))
-    }
-}
-
-impl MaybeFnLike for hir::Expr<'_> {
-    fn is_fn_like(&self) -> bool {
-        matches!(self.kind, hir::ExprKind::Closure(..))
-    }
-}
-
-/// Carries either an FnLikeNode or an Expr, as these are the two
-/// constructs that correspond to "code" (as in, something from which
-/// we can construct a control-flow graph).
-#[derive(Copy, Clone)]
-pub enum Code<'a> {
-    FnLike(FnLikeNode<'a>),
-    Expr(&'a Expr<'a>),
-}
-
-impl<'a> Code<'a> {
-    pub fn id(&self) -> hir::HirId {
-        match *self {
-            Code::FnLike(node) => node.id(),
-            Code::Expr(block) => block.hir_id,
-        }
-    }
-
-    /// Attempts to construct a Code from presumed FnLike or Expr node input.
-    pub fn from_node(map: &Map<'a>, id: hir::HirId) -> Option<Code<'a>> {
-        match map.get(id) {
-            Node::Block(_) => {
-                //  Use the parent, hopefully an expression node.
-                Code::from_node(map, map.get_parent_node(id))
-            }
-            Node::Expr(expr) => Some(Code::Expr(expr)),
-            node => FnLikeNode::from_node(node).map(Code::FnLike),
-        }
-    }
-}
-
-/// These are all the components one can extract from a fn item for
-/// use when implementing FnLikeNode operations.
-struct ItemFnParts<'a> {
-    ident: Ident,
-    decl: &'a hir::FnDecl<'a>,
-    header: hir::FnHeader,
-    vis: &'a hir::Visibility<'a>,
-    generics: &'a hir::Generics<'a>,
-    body: hir::BodyId,
-    id: hir::HirId,
-    span: Span,
-}
-
-/// These are all the components one can extract from a closure expr
-/// for use when implementing FnLikeNode operations.
-struct ClosureParts<'a> {
-    decl: &'a FnDecl<'a>,
-    body: hir::BodyId,
-    id: hir::HirId,
-    span: Span,
-}
-
-impl<'a> ClosureParts<'a> {
-    fn new(d: &'a FnDecl<'a>, b: hir::BodyId, id: hir::HirId, s: Span) -> Self {
-        ClosureParts { decl: d, body: b, id, span: s }
-    }
-}
-
-impl<'a> FnLikeNode<'a> {
-    /// Attempts to construct a FnLikeNode from presumed FnLike node input.
-    pub fn from_node(node: Node<'_>) -> Option<FnLikeNode<'_>> {
-        let fn_like = match node {
-            Node::Item(item) => item.is_fn_like(),
-            Node::TraitItem(tm) => tm.is_fn_like(),
-            Node::ImplItem(it) => it.is_fn_like(),
-            Node::Expr(e) => e.is_fn_like(),
-            _ => false,
-        };
-        fn_like.then_some(FnLikeNode { node })
-    }
-
-    pub fn body(self) -> hir::BodyId {
-        self.handle(
-            |i: ItemFnParts<'a>| i.body,
-            |_, _, _: &'a hir::FnSig<'a>, _, body: hir::BodyId, _| body,
-            |c: ClosureParts<'a>| c.body,
-        )
-    }
-
-    pub fn decl(self) -> &'a FnDecl<'a> {
-        self.handle(
-            |i: ItemFnParts<'a>| &*i.decl,
-            |_, _, sig: &'a hir::FnSig<'a>, _, _, _| &sig.decl,
-            |c: ClosureParts<'a>| c.decl,
-        )
-    }
-
-    pub fn span(self) -> Span {
-        self.handle(
-            |i: ItemFnParts<'_>| i.span,
-            |_, _, _: &'a hir::FnSig<'a>, _, _, span| span,
-            |c: ClosureParts<'_>| c.span,
-        )
-    }
-
-    pub fn id(self) -> hir::HirId {
-        self.handle(
-            |i: ItemFnParts<'_>| i.id,
-            |id, _, _: &'a hir::FnSig<'a>, _, _, _| id,
-            |c: ClosureParts<'_>| c.id,
-        )
-    }
-
-    pub fn constness(self) -> hir::Constness {
-        self.kind().header().map_or(hir::Constness::NotConst, |header| header.constness)
-    }
-
-    pub fn asyncness(self) -> hir::IsAsync {
-        self.kind().header().map_or(hir::IsAsync::NotAsync, |header| header.asyncness)
-    }
-
-    pub fn unsafety(self) -> hir::Unsafety {
-        self.kind().header().map_or(hir::Unsafety::Normal, |header| header.unsafety)
-    }
-
-    pub fn kind(self) -> FnKind<'a> {
-        let item = |p: ItemFnParts<'a>| -> FnKind<'a> {
-            FnKind::ItemFn(p.ident, p.generics, p.header, p.vis)
-        };
-        let closure = |_: ClosureParts<'a>| FnKind::Closure;
-        let method =
-            |_, ident: Ident, sig: &'a hir::FnSig<'a>, vis, _, _| FnKind::Method(ident, sig, vis);
-        self.handle(item, method, closure)
-    }
-
-    fn handle<A, I, M, C>(self, item_fn: I, method: M, closure: C) -> A
-    where
-        I: FnOnce(ItemFnParts<'a>) -> A,
-        M: FnOnce(
-            hir::HirId,
-            Ident,
-            &'a hir::FnSig<'a>,
-            Option<&'a hir::Visibility<'a>>,
-            hir::BodyId,
-            Span,
-        ) -> A,
-        C: FnOnce(ClosureParts<'a>) -> A,
-    {
-        match self.node {
-            Node::Item(i) => match i.kind {
-                hir::ItemKind::Fn(ref sig, ref generics, block) => item_fn(ItemFnParts {
-                    id: i.hir_id(),
-                    ident: i.ident,
-                    decl: &sig.decl,
-                    body: block,
-                    vis: &i.vis,
-                    span: i.span,
-                    header: sig.header,
-                    generics,
-                }),
-                _ => bug!("item FnLikeNode that is not fn-like"),
-            },
-            Node::TraitItem(ti) => match ti.kind {
-                hir::TraitItemKind::Fn(ref sig, hir::TraitFn::Provided(body)) => {
-                    method(ti.hir_id(), ti.ident, sig, None, body, ti.span)
-                }
-                _ => bug!("trait method FnLikeNode that is not fn-like"),
-            },
-            Node::ImplItem(ii) => match ii.kind {
-                hir::ImplItemKind::Fn(ref sig, body) => {
-                    method(ii.hir_id(), ii.ident, sig, Some(&ii.vis), body, ii.span)
-                }
-                _ => bug!("impl method FnLikeNode that is not fn-like"),
-            },
-            Node::Expr(e) => match e.kind {
-                hir::ExprKind::Closure(_, ref decl, block, _fn_decl_span, _gen) => {
-                    closure(ClosureParts::new(&decl, block, e.hir_id, e.span))
-                }
-                _ => bug!("expr FnLikeNode that is not fn-like"),
-            },
-            _ => bug!("other FnLikeNode that is not fn-like"),
-        }
-    }
-}
diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs
index 38bc01b9b53d8..fad7e875fa1c0 100644
--- a/compiler/rustc_middle/src/hir/map/mod.rs
+++ b/compiler/rustc_middle/src/hir/map/mod.rs
@@ -20,8 +20,6 @@ use rustc_span::Span;
 use rustc_target::spec::abi::Abi;
 use std::collections::VecDeque;
 
-pub mod blocks;
-
 fn fn_decl<'hir>(node: Node<'hir>) -> Option<&'hir FnDecl<'hir>> {
     match node {
         Node::Item(Item { kind: ItemKind::Fn(sig, _, _), .. })
diff --git a/compiler/rustc_mir_build/src/lints.rs b/compiler/rustc_mir_build/src/lints.rs
index ef8bd20d51098..e4c2d2dce67c7 100644
--- a/compiler/rustc_mir_build/src/lints.rs
+++ b/compiler/rustc_mir_build/src/lints.rs
@@ -2,7 +2,6 @@ use rustc_data_structures::graph::iterate::{
     NodeStatus, TriColorDepthFirstSearch, TriColorVisitor,
 };
 use rustc_hir::intravisit::FnKind;
-use rustc_middle::hir::map::blocks::FnLikeNode;
 use rustc_middle::mir::{BasicBlock, Body, Operand, TerminatorKind};
 use rustc_middle::ty::subst::{GenericArg, InternalSubsts};
 use rustc_middle::ty::{self, AssocItem, AssocItemContainer, Instance, TyCtxt};
@@ -14,8 +13,8 @@ crate fn check<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
     let def_id = body.source.def_id().expect_local();
     let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
 
-    if let Some(fn_like_node) = FnLikeNode::from_node(tcx.hir().get(hir_id)) {
-        if let FnKind::Closure = fn_like_node.kind() {
+    if let Some(fn_kind) = tcx.hir().get(hir_id).fn_kind() {
+        if let FnKind::Closure = fn_kind {
             // closures can't recur, so they don't matter.
             return;
         }
diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs
index 17790ec91c8a3..63c637af5c21a 100644
--- a/compiler/rustc_mir_transform/src/const_prop.rs
+++ b/compiler/rustc_mir_transform/src/const_prop.rs
@@ -68,11 +68,10 @@ impl<'tcx> MirPass<'tcx> for ConstProp {
             return;
         }
 
-        use rustc_middle::hir::map::blocks::FnLikeNode;
         let def_id = body.source.def_id().expect_local();
         let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
 
-        let is_fn_like = FnLikeNode::from_node(tcx.hir().get(hir_id)).is_some();
+        let is_fn_like = tcx.hir().get(hir_id).fn_kind().is_some();
         let is_assoc_const = tcx.def_kind(def_id.to_def_id()) == DefKind::AssocConst;
 
         // Only run const prop on functions, methods, closures and associated constants
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index e980d3d884f56..4ac93f7161923 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -19,7 +19,6 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
 use rustc_index::vec::IndexVec;
 use rustc_middle::hir;
-use rustc_middle::hir::map::blocks::FnLikeNode;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::mir::coverage::*;
 use rustc_middle::mir::dump_enabled;
@@ -64,7 +63,7 @@ impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
         }
 
         let hir_id = tcx.hir().local_def_id_to_hir_id(mir_source.def_id().expect_local());
-        let is_fn_like = FnLikeNode::from_node(tcx.hir().get(hir_id)).is_some();
+        let is_fn_like = tcx.hir().get(hir_id).fn_kind().is_some();
 
         // Only instrument functions, methods, and closures (not constants since they are evaluated
         // at compile time by Miri).
@@ -74,7 +73,7 @@ impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
         // be tricky if const expressions have no corresponding statements in the enclosing MIR.
         // Closures are carved out by their initial `Assign` statement.)
         if !is_fn_like {
-            trace!("InstrumentCoverage skipped for {:?} (not an FnLikeNode)", mir_source.def_id());
+            trace!("InstrumentCoverage skipped for {:?} (not an fn-like)", mir_source.def_id());
             return;
         }
 
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 60135ef2d8571..ab1fe6fe077a7 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -429,8 +429,7 @@ fn mir_drops_elaborated_and_const_checked<'tcx>(
     }
 
     let hir_id = tcx.hir().local_def_id_to_hir_id(def.did);
-    use rustc_middle::hir::map::blocks::FnLikeNode;
-    let is_fn_like = FnLikeNode::from_node(tcx.hir().get(hir_id)).is_some();
+    let is_fn_like = tcx.hir().get(hir_id).fn_kind().is_some();
     if is_fn_like {
         let did = def.did.to_def_id();
         let def = ty::WithOptConstParam::unknown(did);
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index ae3a9c71c5968..4d4e9432e876d 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -23,7 +23,7 @@ use rustc_middle::span_bug;
 use rustc_middle::thir::abstract_const::Node as ACNode;
 use rustc_middle::ty::fold::TypeVisitor;
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::subst::{InternalSubsts, Subst};
+use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::{self, Const, GenericParamDefKind, TraitRef, Ty, TyCtxt, TypeFoldable};
 use rustc_session::lint;
 use rustc_span::hygiene::Transparency;
@@ -153,11 +153,8 @@ where
         tcx: TyCtxt<'tcx>,
         ct: AbstractConst<'tcx>,
     ) -> ControlFlow<V::BreakTy> {
-        const_evaluatable::walk_abstract_const(tcx, ct, |node| match node.root() {
-            ACNode::Leaf(leaf) => {
-                let leaf = leaf.subst(tcx, ct.substs);
-                self.visit_const(leaf)
-            }
+        const_evaluatable::walk_abstract_const(tcx, ct, |node| match node.root(tcx) {
+            ACNode::Leaf(leaf) => self.visit_const(leaf),
             ACNode::Cast(_, _, ty) => self.visit_ty(ty),
             ACNode::Binop(..) | ACNode::UnaryOp(..) | ACNode::FunctionCall(_, _) => {
                 ControlFlow::CONTINUE
diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
index 1193d10d6a7d7..8edb7069fc45f 100644
--- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
+++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
@@ -80,9 +80,8 @@ pub fn is_const_evaluatable<'cx, 'tcx>(
                     Concrete,
                 }
                 let mut failure_kind = FailureKind::Concrete;
-                walk_abstract_const::<!, _>(tcx, ct, |node| match node.root() {
+                walk_abstract_const::<!, _>(tcx, ct, |node| match node.root(tcx) {
                     Node::Leaf(leaf) => {
-                        let leaf = leaf.subst(tcx, ct.substs);
                         if leaf.has_infer_types_or_consts() {
                             failure_kind = FailureKind::MentionsInfer;
                         } else if leaf.definitely_has_param_types_or_consts(tcx) {
@@ -92,7 +91,6 @@ pub fn is_const_evaluatable<'cx, 'tcx>(
                         ControlFlow::CONTINUE
                     }
                     Node::Cast(_, _, ty) => {
-                        let ty = ty.subst(tcx, ct.substs);
                         if ty.has_infer_types_or_consts() {
                             failure_kind = FailureKind::MentionsInfer;
                         } else if ty.definitely_has_param_types_or_consts(tcx) {
@@ -187,8 +185,8 @@ pub fn is_const_evaluatable<'cx, 'tcx>(
 pub struct AbstractConst<'tcx> {
     // FIXME: Consider adding something like `IndexSlice`
     // and use this here.
-    pub inner: &'tcx [Node<'tcx>],
-    pub substs: SubstsRef<'tcx>,
+    inner: &'tcx [Node<'tcx>],
+    substs: SubstsRef<'tcx>,
 }
 
 impl<'tcx> AbstractConst<'tcx> {
@@ -218,8 +216,14 @@ impl<'tcx> AbstractConst<'tcx> {
     }
 
     #[inline]
-    pub fn root(self) -> Node<'tcx> {
-        self.inner.last().copied().unwrap()
+    pub fn root(self, tcx: TyCtxt<'tcx>) -> Node<'tcx> {
+        let node = self.inner.last().copied().unwrap();
+        match node {
+            Node::Leaf(leaf) => Node::Leaf(leaf.subst(tcx, self.substs)),
+            Node::Cast(kind, operand, ty) => Node::Cast(kind, operand, ty.subst(tcx, self.substs)),
+            // Don't perform substitution on the following as they can't directly contain generic params
+            Node::Binop(_, _, _) | Node::UnaryOp(_, _) | Node::FunctionCall(_, _) => node,
+        }
     }
 }
 
@@ -542,7 +546,7 @@ where
         f: &mut dyn FnMut(AbstractConst<'tcx>) -> ControlFlow<R>,
     ) -> ControlFlow<R> {
         f(ct)?;
-        let root = ct.root();
+        let root = ct.root(tcx);
         match root {
             Node::Leaf(_) => ControlFlow::CONTINUE,
             Node::Binop(_, l, r) => {
@@ -570,16 +574,14 @@ pub(super) fn try_unify<'tcx>(
     // We substitute generics repeatedly to allow AbstractConsts to unify where a
     // ConstKind::Unevalated could be turned into an AbstractConst that would unify e.g.
     // Param(N) should unify with Param(T), substs: [Unevaluated("T2", [Unevaluated("T3", [Param(N)])])]
-    while let Node::Leaf(a_ct) = a.root() {
-        let a_ct = a_ct.subst(tcx, a.substs);
+    while let Node::Leaf(a_ct) = a.root(tcx) {
         match AbstractConst::from_const(tcx, a_ct) {
             Ok(Some(a_act)) => a = a_act,
             Ok(None) => break,
             Err(_) => return true,
         }
     }
-    while let Node::Leaf(b_ct) = b.root() {
-        let b_ct = b_ct.subst(tcx, b.substs);
+    while let Node::Leaf(b_ct) = b.root(tcx) {
         match AbstractConst::from_const(tcx, b_ct) {
             Ok(Some(b_act)) => b = b_act,
             Ok(None) => break,
@@ -587,10 +589,8 @@ pub(super) fn try_unify<'tcx>(
         }
     }
 
-    match (a.root(), b.root()) {
+    match (a.root(tcx), b.root(tcx)) {
         (Node::Leaf(a_ct), Node::Leaf(b_ct)) => {
-            let a_ct = a_ct.subst(tcx, a.substs);
-            let b_ct = b_ct.subst(tcx, b.substs);
             if a_ct.ty != b_ct.ty {
                 return false;
             }
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs
index ad9fd0ca62cfa..afc546540d2e2 100644
--- a/compiler/rustc_trait_selection/src/traits/object_safety.rs
+++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs
@@ -837,14 +837,13 @@ fn contains_illegal_self_type_reference<'tcx, T: TypeFoldable<'tcx>>(
             // constants which are not considered const evaluatable.
             use rustc_middle::thir::abstract_const::Node;
             if let Ok(Some(ct)) = AbstractConst::new(self.tcx, uv.shrink()) {
-                const_evaluatable::walk_abstract_const(self.tcx, ct, |node| match node.root() {
-                    Node::Leaf(leaf) => {
-                        let leaf = leaf.subst(self.tcx, ct.substs);
-                        self.visit_const(leaf)
-                    }
-                    Node::Cast(_, _, ty) => self.visit_ty(ty),
-                    Node::Binop(..) | Node::UnaryOp(..) | Node::FunctionCall(_, _) => {
-                        ControlFlow::CONTINUE
+                const_evaluatable::walk_abstract_const(self.tcx, ct, |node| {
+                    match node.root(self.tcx) {
+                        Node::Leaf(leaf) => self.visit_const(leaf),
+                        Node::Cast(_, _, ty) => self.visit_ty(ty),
+                        Node::Binop(..) | Node::UnaryOp(..) | Node::FunctionCall(_, _) => {
+                            ControlFlow::CONTINUE
+                        }
                     }
                 })
             } else {
diff --git a/compiler/rustc_ty_utils/src/ty.rs b/compiler/rustc_ty_utils/src/ty.rs
index 3d3b274370091..bc77c94809eb5 100644
--- a/compiler/rustc_ty_utils/src/ty.rs
+++ b/compiler/rustc_ty_utils/src/ty.rs
@@ -1,7 +1,6 @@
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_middle::hir::map as hir_map;
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::{
     self, Binder, Predicate, PredicateKind, ToPredicate, Ty, TyCtxt, WithConstness,
@@ -478,11 +477,11 @@ fn asyncness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::IsAsync {
 
     let node = tcx.hir().get(hir_id);
 
-    let fn_like = hir_map::blocks::FnLikeNode::from_node(node).unwrap_or_else(|| {
+    let fn_kind = node.fn_kind().unwrap_or_else(|| {
         bug!("asyncness: expected fn-like node but got `{:?}`", def_id);
     });
 
-    fn_like.asyncness()
+    fn_kind.asyncness()
 }
 
 /// Don't call this directly: use ``tcx.conservative_is_privately_uninhabited`` instead.
diff --git a/compiler/rustc_typeck/src/check/upvar.rs b/compiler/rustc_typeck/src/check/upvar.rs
index caad28ff2b21f..9c7b0b2cacb06 100644
--- a/compiler/rustc_typeck/src/check/upvar.rs
+++ b/compiler/rustc_typeck/src/check/upvar.rs
@@ -883,8 +883,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             self.tcx.get_diagnostic_item(sym::unwind_safe_trait),
             self.tcx.get_diagnostic_item(sym::ref_unwind_safe_trait),
         ];
-        let auto_traits =
-            vec!["`Clone`", "`Sync`", "`Send`", "`Unpin`", "`UnwindSafe`", "`RefUnwindSafe`"];
+        const AUTO_TRAITS: [&str; 6] =
+            ["`Clone`", "`Sync`", "`Send`", "`Unpin`", "`UnwindSafe`", "`RefUnwindSafe`"];
 
         let root_var_min_capture_list = min_captures.and_then(|m| m.get(&var_hir_id))?;
 
@@ -957,7 +957,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // by the root variable but not by the capture
             for (idx, _) in obligations_should_hold.iter().enumerate() {
                 if !obligations_holds_for_capture[idx] && obligations_should_hold[idx] {
-                    capture_problems.insert(auto_traits[idx]);
+                    capture_problems.insert(AUTO_TRAITS[idx]);
                 }
             }
 
@@ -1074,7 +1074,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         min_captures: Option<&ty::RootVariableMinCaptureList<'tcx>>,
     ) -> (Vec<MigrationDiagnosticInfo>, String) {
         let Some(upvars) = self.tcx.upvars_mentioned(closure_def_id) else {
-            return (Vec::new(), format!(""));
+            return (Vec::new(), String::new());
         };
 
         let mut need_migrations = Vec::new();
diff --git a/config.toml.example b/config.toml.example
index 61e57eee782b8..2128fdea2eb46 100644
--- a/config.toml.example
+++ b/config.toml.example
@@ -68,6 +68,12 @@ changelog-seen = 2
 # Indicates whether the LLVM assertions are enabled or not
 #assertions = false
 
+# Indicates whether the LLVM testsuite is enabled in the build or not. Does
+# not execute the tests as part of the build as part of x.py build et al,
+# just makes it possible to do `ninja check-llvm` in the staged LLVM build
+# directory when doing LLVM development as part of Rust development.
+#tests = false
+
 # Indicates whether the LLVM plugin is enabled or not
 #plugins = false
 
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index c890ff4ac5e2b..de607c8fdab31 100644
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/library/alloc/src/collections/vec_deque/mod.rs
@@ -543,9 +543,9 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> VecDeque<T, A> {
+        assert!(capacity < 1_usize << usize::BITS - 1, "capacity overflow");
         // +1 since the ringbuffer always leaves one space empty
         let cap = cmp::max(capacity + 1, MINIMUM_CAPACITY + 1).next_power_of_two();
-        assert!(cap > capacity, "capacity overflow");
 
         VecDeque { tail: 0, head: 0, buf: RawVec::with_capacity_in(cap, alloc) }
     }
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index 20a16869cb3f8..d52c78eedf3fa 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -1305,10 +1305,11 @@ impl<T, A: Allocator> Vec<T, A> {
             // We replace self[index] with the last element. Note that if the
             // bounds check above succeeds there must be a last element (which
             // can be self[index] itself).
-            let last = ptr::read(self.as_ptr().add(len - 1));
-            let hole = self.as_mut_ptr().add(index);
+            let value = ptr::read(self.as_ptr().add(index));
+            let base_ptr = self.as_mut_ptr();
+            ptr::copy(base_ptr.add(len - 1), base_ptr.add(index), 1);
             self.set_len(len - 1);
-            ptr::replace(hole, last)
+            value
         }
     }
 
diff --git a/library/core/src/convert/num.rs b/library/core/src/convert/num.rs
index 75ef873abc965..2b6ea90bf0430 100644
--- a/library/core/src/convert/num.rs
+++ b/library/core/src/convert/num.rs
@@ -390,7 +390,8 @@ use crate::num::NonZeroUsize;
 macro_rules! nzint_impl_from {
     ($Small: ty, $Large: ty, #[$attr:meta], $doc: expr) => {
         #[$attr]
-        impl From<$Small> for $Large {
+        #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
+        impl const From<$Small> for $Large {
             // Rustdocs on the impl block show a "[+] show undocumented items" toggle.
             // Rustdocs on functions do not.
             #[doc = $doc]
@@ -398,7 +399,7 @@ macro_rules! nzint_impl_from {
             fn from(small: $Small) -> Self {
                 // SAFETY: input type guarantees the value is non-zero
                 unsafe {
-                    Self::new_unchecked(small.get().into())
+                    Self::new_unchecked(From::from(small.get()))
                 }
             }
         }
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 13b80c05dbb30..58a170401e7c1 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -115,6 +115,7 @@
 #![feature(const_likely)]
 #![feature(const_maybe_uninit_as_ptr)]
 #![feature(const_maybe_uninit_assume_init)]
+#![feature(const_num_from_num)]
 #![feature(const_option)]
 #![feature(const_pin)]
 #![feature(const_replace)]
diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index d28474c29232c..9b1a4de5d8037 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -82,7 +82,7 @@ macro_rules! nonzero_integers {
             }
 
             #[stable(feature = "from_nonzero", since = "1.31.0")]
-            #[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+            #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
             impl const From<$Ty> for $Int {
                 #[doc = concat!("Converts a `", stringify!($Ty), "` into an `", stringify!($Int), "`")]
                 #[inline]
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs
index 0915dcffe6ef0..1dd3b2d8e3c8d 100644
--- a/library/core/src/sync/atomic.rs
+++ b/library/core/src/sync/atomic.rs
@@ -1365,7 +1365,7 @@ macro_rules! atomic_int {
         }
 
         #[$stable_from]
-        #[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+        #[rustc_const_unstable(feature = "const_num_from_num", issue = "87852")]
         impl const From<$int_type> for $atomic_type {
             #[doc = concat!("Converts an `", stringify!($int_type), "` into an `", stringify!($atomic_type), "`.")]
             #[inline]
diff --git a/library/core/tests/nonzero.rs b/library/core/tests/nonzero.rs
index 4817d86ca6eb0..a0ca919a851c3 100644
--- a/library/core/tests/nonzero.rs
+++ b/library/core/tests/nonzero.rs
@@ -204,9 +204,9 @@ fn nonzero_const() {
     // test that the methods of `NonZeroX>` are usable in a const context
     // Note: only tests NonZero8
 
-    const NONZERO: NonZeroU8 = unsafe { NonZeroU8::new_unchecked(5) };
+    const NONZERO_U8: NonZeroU8 = unsafe { NonZeroU8::new_unchecked(5) };
 
-    const GET: u8 = NONZERO.get();
+    const GET: u8 = NONZERO_U8.get();
     assert_eq!(GET, 5);
 
     const ZERO: Option<NonZeroU8> = NonZeroU8::new(0);
@@ -215,8 +215,11 @@ fn nonzero_const() {
     const ONE: Option<NonZeroU8> = NonZeroU8::new(1);
     assert!(ONE.is_some());
 
-    const FROM_NONZERO: u8 = u8::from(NONZERO);
-    assert_eq!(FROM_NONZERO, 5);
+    const FROM_NONZERO_U8: u8 = u8::from(NONZERO_U8);
+    assert_eq!(FROM_NONZERO_U8, 5);
+
+    const NONZERO_CONVERT: NonZeroU32 = NonZeroU32::from(NONZERO_U8);
+    assert_eq!(NONZERO_CONVERT.get(), 5);
 }
 
 #[test]
diff --git a/library/std/src/ffi/c_str.rs b/library/std/src/ffi/c_str.rs
index 6827d3a8d2448..cb09717bde577 100644
--- a/library/std/src/ffi/c_str.rs
+++ b/library/std/src/ffi/c_str.rs
@@ -251,13 +251,12 @@ pub struct FromBytesWithNulError {
 /// # Examples
 ///
 /// ```
-/// #![feature(cstring_from_vec_with_nul)]
 /// use std::ffi::{CString, FromVecWithNulError};
 ///
 /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"f\0oo".to_vec()).unwrap_err();
 /// ```
 #[derive(Clone, PartialEq, Eq, Debug)]
-#[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
 pub struct FromVecWithNulError {
     error_kind: FromBytesWithNulErrorKind,
     bytes: Vec<u8>,
@@ -278,7 +277,7 @@ impl FromBytesWithNulError {
     }
 }
 
-#[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
 impl FromVecWithNulError {
     /// Returns a slice of [`u8`]s bytes that were attempted to convert to a [`CString`].
     ///
@@ -287,7 +286,6 @@ impl FromVecWithNulError {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(cstring_from_vec_with_nul)]
     /// use std::ffi::CString;
     ///
     /// // Some invalid bytes in a vector
@@ -298,6 +296,7 @@ impl FromVecWithNulError {
     /// assert_eq!(&bytes[..], value.unwrap_err().as_bytes());
     /// ```
     #[must_use]
+    #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
     pub fn as_bytes(&self) -> &[u8] {
         &self.bytes[..]
     }
@@ -313,7 +312,6 @@ impl FromVecWithNulError {
     /// Basic usage:
     ///
     /// ```
-    /// #![feature(cstring_from_vec_with_nul)]
     /// use std::ffi::CString;
     ///
     /// // Some invalid bytes in a vector
@@ -324,6 +322,7 @@ impl FromVecWithNulError {
     /// assert_eq!(bytes, value.unwrap_err().into_bytes());
     /// ```
     #[must_use = "`self` will be dropped if the result is not used"]
+    #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
     pub fn into_bytes(self) -> Vec<u8> {
         self.bytes
     }
@@ -704,7 +703,6 @@ impl CString {
     /// # Example
     ///
     /// ```
-    /// #![feature(cstring_from_vec_with_nul)]
     /// use std::ffi::CString;
     /// assert_eq!(
     ///     unsafe { CString::from_vec_with_nul_unchecked(b"abc\0".to_vec()) },
@@ -712,7 +710,7 @@ impl CString {
     /// );
     /// ```
     #[must_use]
-    #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
+    #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
     pub unsafe fn from_vec_with_nul_unchecked(v: Vec<u8>) -> Self {
         Self { inner: v.into_boxed_slice() }
     }
@@ -733,7 +731,6 @@ impl CString {
     /// when called without the ending nul byte.
     ///
     /// ```
-    /// #![feature(cstring_from_vec_with_nul)]
     /// use std::ffi::CString;
     /// assert_eq!(
     ///     CString::from_vec_with_nul(b"abc\0".to_vec())
@@ -745,14 +742,13 @@ impl CString {
     /// An incorrectly formatted [`Vec`] will produce an error.
     ///
     /// ```
-    /// #![feature(cstring_from_vec_with_nul)]
     /// use std::ffi::{CString, FromVecWithNulError};
     /// // Interior nul byte
     /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"a\0bc".to_vec()).unwrap_err();
     /// // No nul byte
     /// let _: FromVecWithNulError = CString::from_vec_with_nul(b"abc".to_vec()).unwrap_err();
     /// ```
-    #[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
+    #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
     pub fn from_vec_with_nul(v: Vec<u8>) -> Result<Self, FromVecWithNulError> {
         let nul_pos = memchr::memchr(0, &v);
         match nul_pos {
@@ -1084,10 +1080,10 @@ impl fmt::Display for FromBytesWithNulError {
     }
 }
 
-#[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
 impl Error for FromVecWithNulError {}
 
-#[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
 impl fmt::Display for FromVecWithNulError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.error_kind {
diff --git a/library/std/src/ffi/mod.rs b/library/std/src/ffi/mod.rs
index 82a76aa73c583..7f3bb836754ed 100644
--- a/library/std/src/ffi/mod.rs
+++ b/library/std/src/ffi/mod.rs
@@ -145,7 +145,7 @@
 
 #[stable(feature = "cstr_from_bytes", since = "1.10.0")]
 pub use self::c_str::FromBytesWithNulError;
-#[unstable(feature = "cstring_from_vec_with_nul", issue = "73179")]
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
 pub use self::c_str::FromVecWithNulError;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::c_str::{CStr, CString, IntoStringError, NulError};
diff --git a/library/std/src/net/ip.rs b/library/std/src/net/ip.rs
index e5e9fedb61eaf..c080f783cbb36 100644
--- a/library/std/src/net/ip.rs
+++ b/library/std/src/net/ip.rs
@@ -59,7 +59,8 @@ pub enum IpAddr {
 ///
 /// `Ipv4Addr` provides a [`FromStr`] implementation. The four octets are in decimal
 /// notation, divided by `.` (this is called "dot-decimal notation").
-/// Notably, octal numbers and hexadecimal numbers are not allowed per [IETF RFC 6943].
+/// Notably, octal numbers (which are indicated with a leading `0`) and hexadecimal numbers (which
+/// are indicated with a leading `0x`) are not allowed per [IETF RFC 6943].
 ///
 /// [IETF RFC 6943]: https://tools.ietf.org/html/rfc6943#section-3.1.1
 /// [`FromStr`]: crate::str::FromStr
@@ -72,6 +73,9 @@ pub enum IpAddr {
 /// let localhost = Ipv4Addr::new(127, 0, 0, 1);
 /// assert_eq!("127.0.0.1".parse(), Ok(localhost));
 /// assert_eq!(localhost.is_loopback(), true);
+/// assert!("012.004.002.000".parse::<Ipv4Addr>().is_err()); // all octets are in octal
+/// assert!("0000000.0.0.0".parse::<Ipv4Addr>().is_err()); // first octet is a zero in octal
+/// assert!("0xcb.0x0.0x71.0x00".parse::<Ipv4Addr>().is_err()); // all octets are in hex
 /// ```
 #[derive(Copy)]
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/std/src/net/ip/tests.rs b/library/std/src/net/ip/tests.rs
index babc854cd1d33..17581f330266d 100644
--- a/library/std/src/net/ip/tests.rs
+++ b/library/std/src/net/ip/tests.rs
@@ -20,6 +20,14 @@ fn test_from_str_ipv4() {
     // no number between dots
     let none: Option<Ipv4Addr> = "255.0..1".parse().ok();
     assert_eq!(None, none);
+    // octal
+    let none: Option<Ipv4Addr> = "255.0.0.01".parse().ok();
+    assert_eq!(None, none);
+    // octal zero
+    let none: Option<Ipv4Addr> = "255.0.0.00".parse().ok();
+    assert_eq!(None, none);
+    let none: Option<Ipv4Addr> = "255.0.00.0".parse().ok();
+    assert_eq!(None, none);
 }
 
 #[test]
diff --git a/library/std/src/net/parser.rs b/library/std/src/net/parser.rs
index 88a8cb76befbf..4e16a55edece2 100644
--- a/library/std/src/net/parser.rs
+++ b/library/std/src/net/parser.rs
@@ -111,10 +111,12 @@ impl<'a> Parser<'a> {
         &mut self,
         radix: u32,
         max_digits: Option<usize>,
+        allow_zero_prefix: bool,
     ) -> Option<T> {
         self.read_atomically(move |p| {
             let mut result = T::ZERO;
             let mut digit_count = 0;
+            let has_leading_zero = p.peek_char() == Some('0');
 
             while let Some(digit) = p.read_atomically(|p| p.read_char()?.to_digit(radix)) {
                 result = result.checked_mul(radix)?;
@@ -127,7 +129,13 @@ impl<'a> Parser<'a> {
                 }
             }
 
-            if digit_count == 0 { None } else { Some(result) }
+            if digit_count == 0 {
+                None
+            } else if !allow_zero_prefix && has_leading_zero && digit_count > 1 {
+                None
+            } else {
+                Some(result)
+            }
         })
     }
 
@@ -140,10 +148,7 @@ impl<'a> Parser<'a> {
                 *slot = p.read_separator('.', i, |p| {
                     // Disallow octal number in IP string.
                     // https://tools.ietf.org/html/rfc6943#section-3.1.1
-                    match (p.peek_char(), p.read_number(10, None)) {
-                        (Some('0'), Some(number)) if number != 0 => None,
-                        (_, number) => number,
-                    }
+                    p.read_number(10, Some(3), false)
                 })?;
             }
 
@@ -175,7 +180,7 @@ impl<'a> Parser<'a> {
                     }
                 }
 
-                let group = p.read_separator(':', i, |p| p.read_number(16, Some(4)));
+                let group = p.read_separator(':', i, |p| p.read_number(16, Some(4), true));
 
                 match group {
                     Some(g) => *slot = g,
@@ -227,7 +232,7 @@ impl<'a> Parser<'a> {
     fn read_port(&mut self) -> Option<u16> {
         self.read_atomically(|p| {
             p.read_given_char(':')?;
-            p.read_number(10, None)
+            p.read_number(10, None, true)
         })
     }
 
@@ -235,7 +240,7 @@ impl<'a> Parser<'a> {
     fn read_scope_id(&mut self) -> Option<u32> {
         self.read_atomically(|p| {
             p.read_given_char('%')?;
-            p.read_number(10, None)
+            p.read_number(10, None, true)
         })
     }
 
@@ -281,7 +286,12 @@ impl FromStr for IpAddr {
 impl FromStr for Ipv4Addr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<Ipv4Addr, AddrParseError> {
-        Parser::new(s).parse_with(|p| p.read_ipv4_addr())
+        // don't try to parse if too long
+        if s.len() > 15 {
+            Err(AddrParseError(()))
+        } else {
+            Parser::new(s).parse_with(|p| p.read_ipv4_addr())
+        }
     }
 }
 
diff --git a/library/std/src/sync/barrier.rs b/library/std/src/sync/barrier.rs
index 133c3e46cd8a6..11836b7b694b3 100644
--- a/library/std/src/sync/barrier.rs
+++ b/library/std/src/sync/barrier.rs
@@ -130,7 +130,7 @@ impl Barrier {
         if lock.count < self.num_threads {
             // We need a while loop to guard against spurious wakeups.
             // https://en.wikipedia.org/wiki/Spurious_wakeup
-            while local_gen == lock.generation_id && lock.count < self.num_threads {
+            while local_gen == lock.generation_id {
                 lock = self.cvar.wait(lock).unwrap();
             }
             BarrierWaitResult(false)
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 9a48b768cb37d..8d03aade3413a 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -90,6 +90,7 @@ pub struct Config {
     // llvm codegen options
     pub llvm_skip_rebuild: bool,
     pub llvm_assertions: bool,
+    pub llvm_tests: bool,
     pub llvm_plugins: bool,
     pub llvm_optimize: bool,
     pub llvm_thin_lto: bool,
@@ -422,6 +423,7 @@ struct Llvm {
     thin_lto: Option<bool>,
     release_debuginfo: Option<bool>,
     assertions: Option<bool>,
+    tests: Option<bool>,
     plugins: Option<bool>,
     ccache: Option<StringOrBool>,
     version_check: Option<bool>,
@@ -715,6 +717,7 @@ impl Config {
         // Store off these values as options because if they're not provided
         // we'll infer default values for them later
         let mut llvm_assertions = None;
+        let mut llvm_tests = None;
         let mut llvm_plugins = None;
         let mut debug = None;
         let mut debug_assertions = None;
@@ -740,6 +743,7 @@ impl Config {
             }
             set(&mut config.ninja_in_file, llvm.ninja);
             llvm_assertions = llvm.assertions;
+            llvm_tests = llvm.tests;
             llvm_plugins = llvm.plugins;
             llvm_skip_rebuild = llvm_skip_rebuild.or(llvm.skip_rebuild);
             set(&mut config.llvm_optimize, llvm.optimize);
@@ -991,6 +995,7 @@ impl Config {
 
         config.llvm_skip_rebuild = llvm_skip_rebuild.unwrap_or(false);
         config.llvm_assertions = llvm_assertions.unwrap_or(false);
+        config.llvm_tests = llvm_tests.unwrap_or(false);
         config.llvm_plugins = llvm_plugins.unwrap_or(false);
         config.rust_optimize = optimize.unwrap_or(true);
 
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index 27c9bb2504f6d..6bfaeffa80705 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -170,6 +170,7 @@ impl Step for Llvm {
 
         let assertions = if builder.config.llvm_assertions { "ON" } else { "OFF" };
         let plugins = if builder.config.llvm_plugins { "ON" } else { "OFF" };
+        let enable_tests = if builder.config.llvm_tests { "ON" } else { "OFF" };
 
         cfg.out_dir(&out_dir)
             .profile(profile)
@@ -180,7 +181,7 @@ impl Step for Llvm {
             .define("LLVM_INCLUDE_EXAMPLES", "OFF")
             .define("LLVM_INCLUDE_DOCS", "OFF")
             .define("LLVM_INCLUDE_BENCHMARKS", "OFF")
-            .define("LLVM_INCLUDE_TESTS", "OFF")
+            .define("LLVM_INCLUDE_TESTS", enable_tests)
             .define("LLVM_ENABLE_TERMINFO", "OFF")
             .define("LLVM_ENABLE_LIBEDIT", "OFF")
             .define("LLVM_ENABLE_BINDINGS", "OFF")
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
index adc970c66d688..ba4e1ca31148c 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
@@ -72,7 +72,7 @@ ENV PATH="/node-v14.4.0-linux-x64/bin:${PATH}"
 # https://github.com/puppeteer/puppeteer/issues/375
 #
 # We also specify the version in case we need to update it to go around cache limitations.
-RUN npm install -g browser-ui-test@0.4.3 --unsafe-perm=true
+RUN npm install -g browser-ui-test@0.4.5 --unsafe-perm=true
 
 ENV RUST_CONFIGURE_ARGS \
   --build=x86_64-unknown-linux-gnu \
diff --git a/src/test/incremental/auxiliary/rustc-rust-log-aux.rs b/src/test/incremental/auxiliary/rustc-rust-log-aux.rs
new file mode 100644
index 0000000000000..a361373dc1955
--- /dev/null
+++ b/src/test/incremental/auxiliary/rustc-rust-log-aux.rs
@@ -0,0 +1,8 @@
+// rustc-env:RUSTC_LOG=debug
+#[cfg(rpass1)]
+pub fn foo() {}
+
+#[cfg(rpass2)]
+pub fn foo() {
+    println!();
+}
diff --git a/src/test/incremental/rustc-rust-log.rs b/src/test/incremental/rustc-rust-log.rs
new file mode 100644
index 0000000000000..566f0d96d9732
--- /dev/null
+++ b/src/test/incremental/rustc-rust-log.rs
@@ -0,0 +1,16 @@
+// revisions: rpass1 rpass2
+// This test is just checking that we won't ICE if logging is turned
+// on; don't bother trying to compare that (copious) output.
+//
+// dont-check-compiler-stdout
+// dont-check-compiler-stderr
+// aux-build: rustc-rust-log-aux.rs
+// rustc-env:RUSTC_LOG=debug
+
+#[cfg(rpass1)]
+fn main() {}
+
+#[cfg(rpass2)]
+fn main() {
+    println!();
+}
diff --git a/src/test/rustdoc-gui/docblock-code-block-line-number.goml b/src/test/rustdoc-gui/docblock-code-block-line-number.goml
new file mode 100644
index 0000000000000..7e6607b55ea8b
--- /dev/null
+++ b/src/test/rustdoc-gui/docblock-code-block-line-number.goml
@@ -0,0 +1,22 @@
+// Checks that the setting "line numbers" is working as expected.
+goto: file://|DOC_PATH|/test_docs/fn.foo.html
+
+// We check that without this setting, there is no line number displayed.
+assert-false: "pre.line-number"
+
+// We now set the setting to show the line numbers on code examples.
+local-storage: {"rustdoc-line-numbers": "true" }
+// We reload to make the line numbers appear.
+reload:
+
+// We wait for them to be added into the DOM by the JS...
+wait-for: "pre.line-number"
+// If the test didn't fail, it means that it was found!
+// Let's now check some CSS properties...
+assert-css: ("pre.line-number", {
+    "margin": "0px",
+    "padding": "13px 8px",
+    "text-align": "right"
+})
+// The first code block has two lines so let's check its `<pre>` elements lists both of them.
+assert-text: ("pre.line-number", "1\n2")
diff --git a/src/test/rustdoc-gui/sidebar-macro-reexport.goml b/src/test/rustdoc-gui/sidebar-macro-reexport.goml
new file mode 100644
index 0000000000000..a3a62fe54465e
--- /dev/null
+++ b/src/test/rustdoc-gui/sidebar-macro-reexport.goml
@@ -0,0 +1,5 @@
+// This test ensures that the reexport of a macro doesn't make the original macro
+// displayed twice in the sidebar.
+goto: file://|DOC_PATH|/test_docs/macro.repro.html
+wait-for: ".sidebar-elems .macro .macro"
+assert-count: ("//*[@class='sidebar-elems']//*[@class='block macro']//a[text()='repro']", 1)
diff --git a/src/test/rustdoc-gui/sidebar.goml b/src/test/rustdoc-gui/sidebar.goml
index c8ebb8c56f535..62dc76a40bcf5 100644
--- a/src/test/rustdoc-gui/sidebar.goml
+++ b/src/test/rustdoc-gui/sidebar.goml
@@ -7,12 +7,13 @@ assert-text: (".sidebar-elems > #all-types", "See all test_docs's items")
 assert-text: (".sidebar-elems > .crate > ul > li > a.current", "test_docs")
 // And we're also supposed to have the list of items in the current module.
 assert-text: (".sidebar-elems > .items > ul > li:nth-child(1)", "Modules")
-assert-text: (".sidebar-elems > .items > ul > li:nth-child(2)", "Structs")
-assert-text: (".sidebar-elems > .items > ul > li:nth-child(3)", "Enums")
-assert-text: (".sidebar-elems > .items > ul > li:nth-child(4)", "Traits")
-assert-text: (".sidebar-elems > .items > ul > li:nth-child(5)", "Functions")
-assert-text: (".sidebar-elems > .items > ul > li:nth-child(6)", "Type Definitions")
-assert-text: (".sidebar-elems > .items > ul > li:nth-child(7)", "Keywords")
+assert-text: (".sidebar-elems > .items > ul > li:nth-child(2)", "Macros")
+assert-text: (".sidebar-elems > .items > ul > li:nth-child(3)", "Structs")
+assert-text: (".sidebar-elems > .items > ul > li:nth-child(4)", "Enums")
+assert-text: (".sidebar-elems > .items > ul > li:nth-child(5)", "Traits")
+assert-text: (".sidebar-elems > .items > ul > li:nth-child(6)", "Functions")
+assert-text: (".sidebar-elems > .items > ul > li:nth-child(7)", "Type Definitions")
+assert-text: (".sidebar-elems > .items > ul > li:nth-child(8)", "Keywords")
 assert-text: ("#structs + .item-table .item-left > a", "Foo")
 click: "#structs + .item-table .item-left > a"
 
diff --git a/src/test/rustdoc-gui/src/test_docs/lib.rs b/src/test/rustdoc-gui/src/test_docs/lib.rs
index 2a147e64d8bf2..652308a71cb85 100644
--- a/src/test/rustdoc-gui/src/test_docs/lib.rs
+++ b/src/test/rustdoc-gui/src/test_docs/lib.rs
@@ -12,6 +12,7 @@ use std::fmt;
 ///
 /// ```
 /// println!("nothing fancy");
+/// println!("but with two lines!");
 /// ```
 ///
 /// A failing to compile one:
@@ -123,3 +124,10 @@ pub mod huge_amount_of_consts {
 
 /// Very long code text `hereIgoWithLongTextBecauseWhyNotAndWhyWouldntI`.
 pub mod long_code_block {}
+
+#[macro_export]
+macro_rules! repro {
+    () => {};
+}
+
+pub use crate::repro as repro2;
diff --git a/src/test/rustdoc-ui/doc-without-codeblock.rs b/src/test/rustdoc-ui/doc-without-codeblock.rs
index 6812a454157b9..315fca195873a 100644
--- a/src/test/rustdoc-ui/doc-without-codeblock.rs
+++ b/src/test/rustdoc-ui/doc-without-codeblock.rs
@@ -11,3 +11,12 @@ pub mod foo {
     //~^ ERROR missing code example in this documentation
     pub fn bar() {}
 }
+
+// This impl is here to ensure the lint isn't emitted for foreign traits implementations.
+impl std::ops::Neg for Foo {
+    type Output = Self;
+
+    fn neg(self) -> Self::Output {
+        Self
+    }
+}
diff --git a/src/test/rustdoc-ui/doc-without-codeblock.stderr b/src/test/rustdoc-ui/doc-without-codeblock.stderr
index aac537e9783cd..1c138044165f2 100644
--- a/src/test/rustdoc-ui/doc-without-codeblock.stderr
+++ b/src/test/rustdoc-ui/doc-without-codeblock.stderr
@@ -6,7 +6,7 @@ LL | |
 LL | | /// Some docs.
 LL | |
 ...  |
-LL | |     pub fn bar() {}
+LL | |     }
 LL | | }
    | |_^
    |
diff --git a/src/test/ui/rustc-rust-log.rs b/src/test/ui/rustc-rust-log.rs
index 8ceb24dd2afd2..52e7dcf4499a8 100644
--- a/src/test/ui/rustc-rust-log.rs
+++ b/src/test/ui/rustc-rust-log.rs
@@ -1,9 +1,6 @@
 // run-pass
 // This test is just checking that we won't ICE if logging is turned
-// on; don't bother trying to compare that (copious) output. (Note
-// also that this test potentially silly, since we do not build+test
-// debug versions of rustc as part of our continuous integration
-// process...)
+// on; don't bother trying to compare that (copious) output.
 //
 // dont-check-compiler-stdout
 // dont-check-compiler-stderr