diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index c7fa8e788b573..576267e6948f5 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -775,6 +775,10 @@ pub fn build_codegen_backend(builder: &Builder<'_>,
                     cargo.env("CFG_LLVM_ROOT", s);
                 }
             }
+            // Some LLVM linker flags (-L and -l) may be needed to link librustc_llvm.
+            if let Some(ref s) = builder.config.llvm_ldflags {
+                cargo.env("LLVM_LINKER_FLAGS", s);
+            }
             // Building with a static libstdc++ is only supported on linux right now,
             // not for MSVC or macOS
             if builder.config.llvm_static_stdcpp &&
diff --git a/src/bootstrap/dist.rs b/src/bootstrap/dist.rs
index 274961916183a..45bc77ec97d47 100644
--- a/src/bootstrap/dist.rs
+++ b/src/bootstrap/dist.rs
@@ -804,6 +804,7 @@ fn copy_src_dirs(builder: &Builder<'_>, src_dirs: &[&str], exclude_dirs: &[&str]
 
         const LLVM_PROJECTS: &[&str] = &[
             "llvm-project/clang", "llvm-project\\clang",
+            "llvm-project/libunwind", "llvm-project\\libunwind",
             "llvm-project/lld", "llvm-project\\lld",
             "llvm-project/lldb", "llvm-project\\lldb",
             "llvm-project/llvm", "llvm-project\\llvm",
diff --git a/src/liballoc/collections/vec_deque.rs b/src/liballoc/collections/vec_deque.rs
index 31e49d06a7b5a..71faf672962b3 100644
--- a/src/liballoc/collections/vec_deque.rs
+++ b/src/liballoc/collections/vec_deque.rs
@@ -2709,6 +2709,11 @@ impl<T: fmt::Debug> fmt::Debug for VecDeque<T> {
 
 #[stable(feature = "vecdeque_vec_conversions", since = "1.10.0")]
 impl<T> From<Vec<T>> for VecDeque<T> {
+    /// Turn a [`Vec<T>`] into a [`VecDeque<T>`].
+    ///
+    /// This avoids reallocating where possible, but the conditions for that are
+    /// strict, and subject to change, and so shouldn't be relied upon unless the
+    /// `Vec<T>` came from `From<VecDeque<T>>` and hasn't been reallocated.
     fn from(mut other: Vec<T>) -> Self {
         unsafe {
             let other_buf = other.as_mut_ptr();
@@ -2735,6 +2740,32 @@ impl<T> From<Vec<T>> for VecDeque<T> {
 
 #[stable(feature = "vecdeque_vec_conversions", since = "1.10.0")]
 impl<T> From<VecDeque<T>> for Vec<T> {
+    /// Turn a [`VecDeque<T>`] into a [`Vec<T>`].
+    ///
+    /// This never needs to re-allocate, but does need to do O(n) data movement if
+    /// the circular buffer doesn't happen to be at the beginning of the allocation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use std::collections::VecDeque;
+    ///
+    /// // This one is O(1).
+    /// let deque: VecDeque<_> = (1..5).collect();
+    /// let ptr = deque.as_slices().0.as_ptr();
+    /// let vec = Vec::from(deque);
+    /// assert_eq!(vec, [1, 2, 3, 4]);
+    /// assert_eq!(vec.as_ptr(), ptr);
+    ///
+    /// // This one needs data rearranging.
+    /// let mut deque: VecDeque<_> = (1..5).collect();
+    /// deque.push_front(9);
+    /// deque.push_front(8);
+    /// let ptr = deque.as_slices().1.as_ptr();
+    /// let vec = Vec::from(deque);
+    /// assert_eq!(vec, [8, 9, 1, 2, 3, 4]);
+    /// assert_eq!(vec.as_ptr(), ptr);
+    /// ```
     fn from(other: VecDeque<T>) -> Self {
         unsafe {
             let buf = other.buf.ptr();
diff --git a/src/librustc/infer/opaque_types/mod.rs b/src/librustc/infer/opaque_types/mod.rs
index 8e9af8b39385f..1c52b5775a0cc 100644
--- a/src/librustc/infer/opaque_types/mod.rs
+++ b/src/librustc/infer/opaque_types/mod.rs
@@ -307,7 +307,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
 
             let required_region_bounds = tcx.required_region_bounds(
                 opaque_type,
-                bounds.predicates.clone(),
+                bounds.predicates,
             );
             debug_assert!(!required_region_bounds.is_empty());
 
diff --git a/src/librustc/middle/liveness.rs b/src/librustc/middle/liveness.rs
index 260935a38d6d4..29c624575c3c2 100644
--- a/src/librustc/middle/liveness.rs
+++ b/src/librustc/middle/liveness.rs
@@ -1617,7 +1617,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
                     self.ir.tcx.lint_hir_note(
                         lint::builtin::UNUSED_VARIABLES,
                         hir_id,
-                        spans.clone(),
+                        spans,
                         &format!("variable `{}` is assigned to, but never used", name),
                         &format!("consider using `_{}` instead", name),
                     );
diff --git a/src/librustc_borrowck/borrowck/check_loans.rs b/src/librustc_borrowck/borrowck/check_loans.rs
index 4a36d441d3d9f..54989db46c1c5 100644
--- a/src/librustc_borrowck/borrowck/check_loans.rs
+++ b/src/librustc_borrowck/borrowck/check_loans.rs
@@ -36,7 +36,7 @@ fn owned_ptr_base_path<'a, 'tcx>(loan_path: &'a LoanPath<'tcx>) -> &'a LoanPath<
 
     return match helper(loan_path) {
         Some(new_loan_path) => new_loan_path,
-        None => loan_path.clone()
+        None => loan_path,
     };
 
     fn helper<'a, 'tcx>(loan_path: &'a LoanPath<'tcx>) -> Option<&'a LoanPath<'tcx>> {
diff --git a/src/librustc_codegen_llvm/back/lto.rs b/src/librustc_codegen_llvm/back/lto.rs
index 74cda2d2fd182..5d3cc0c0a255f 100644
--- a/src/librustc_codegen_llvm/back/lto.rs
+++ b/src/librustc_codegen_llvm/back/lto.rs
@@ -279,7 +279,7 @@ fn fat_lto(cgcx: &CodegenContext<LlvmCodegenBackend>,
             }
         }));
         serialized_modules.extend(cached_modules.into_iter().map(|(buffer, wp)| {
-            (buffer, CString::new(wp.cgu_name.clone()).unwrap())
+            (buffer, CString::new(wp.cgu_name).unwrap())
         }));
 
         // For all serialized bitcode files we parse them and link them in as we did
diff --git a/src/librustc_codegen_llvm/context.rs b/src/librustc_codegen_llvm/context.rs
index 967fe877fd1ad..588f7481cc060 100644
--- a/src/librustc_codegen_llvm/context.rs
+++ b/src/librustc_codegen_llvm/context.rs
@@ -459,7 +459,7 @@ impl CodegenCx<'b, 'tcx> {
         };
         let f = self.declare_cfn(name, fn_ty);
         llvm::SetUnnamedAddr(f, false);
-        self.intrinsics.borrow_mut().insert(name, f.clone());
+        self.intrinsics.borrow_mut().insert(name, f);
         f
     }
 
diff --git a/src/librustc_codegen_llvm/debuginfo/metadata.rs b/src/librustc_codegen_llvm/debuginfo/metadata.rs
index d43adc9cb92c5..fbeda43af42b0 100644
--- a/src/librustc_codegen_llvm/debuginfo/metadata.rs
+++ b/src/librustc_codegen_llvm/debuginfo/metadata.rs
@@ -1609,7 +1609,7 @@ impl<'tcx> VariantInfo<'tcx> {
                 // with every variant, make each variant name be just the value
                 // of the discriminant. The struct name for the variant includes
                 // the actual variant description.
-                format!("{}", variant_index.as_usize()).to_string()
+                format!("{}", variant_index.as_usize())
             }
         }
     }
diff --git a/src/librustc_errors/annotate_snippet_emitter_writer.rs b/src/librustc_errors/annotate_snippet_emitter_writer.rs
index 9f9c7588d977b..7ed2fddf72d23 100644
--- a/src/librustc_errors/annotate_snippet_emitter_writer.rs
+++ b/src/librustc_errors/annotate_snippet_emitter_writer.rs
@@ -194,7 +194,7 @@ impl AnnotateSnippetEmitterWriter {
         let converter = DiagnosticConverter {
             source_map: self.source_map.clone(),
             level: level.clone(),
-            message: message.clone(),
+            message,
             code: code.clone(),
             msp: msp.clone(),
             children,
diff --git a/src/librustc_llvm/build.rs b/src/librustc_llvm/build.rs
index 7fa83dd977950..21fa872c8dadb 100644
--- a/src/librustc_llvm/build.rs
+++ b/src/librustc_llvm/build.rs
@@ -234,6 +234,21 @@ fn main() {
         }
     }
 
+    // Some LLVM linker flags (-L and -l) may be needed even when linking
+    // librustc_llvm, for example when using static libc++, we may need to
+    // manually specify the library search path and -ldl -lpthread as link
+    // dependencies.
+    let llvm_linker_flags = env::var_os("LLVM_LINKER_FLAGS");
+    if let Some(s) = llvm_linker_flags {
+        for lib in s.into_string().unwrap().split_whitespace() {
+            if lib.starts_with("-l") {
+                println!("cargo:rustc-link-lib={}", &lib[2..]);
+            } else if lib.starts_with("-L") {
+                println!("cargo:rustc-link-search=native={}", &lib[2..]);
+            }
+        }
+    }
+
     let llvm_static_stdcpp = env::var_os("LLVM_STATIC_STDCPP");
     let llvm_use_libcxx = env::var_os("LLVM_USE_LIBCXX");
 
diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index 7ffba41e2569a..5fef8e53e1d0c 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -236,7 +236,7 @@ impl<'a> CrateLoader<'a> {
                 let host_lib = host_lib.unwrap();
                 self.load_derive_macros(
                     &host_lib.metadata.get_root(),
-                    host_lib.dylib.clone().map(|p| p.0),
+                    host_lib.dylib.map(|p| p.0),
                     span
                 )
             } else {
diff --git a/src/librustc_mir/build/matches/mod.rs b/src/librustc_mir/build/matches/mod.rs
index 4f73c92be504e..f9e503ee69b12 100644
--- a/src/librustc_mir/build/matches/mod.rs
+++ b/src/librustc_mir/build/matches/mod.rs
@@ -1737,7 +1737,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 pat_span,
             }))),
         };
-        let for_arm_body = self.local_decls.push(local.clone());
+        let for_arm_body = self.local_decls.push(local);
         let locals = if has_guard.0 {
             let ref_for_guard = self.local_decls.push(LocalDecl::<'tcx> {
                 // This variable isn't mutated but has a name, so has to be
diff --git a/src/librustc_typeck/check/wfcheck.rs b/src/librustc_typeck/check/wfcheck.rs
index 77ac2b96160a6..bf64643e5a745 100644
--- a/src/librustc_typeck/check/wfcheck.rs
+++ b/src/librustc_typeck/check/wfcheck.rs
@@ -922,7 +922,7 @@ fn receiver_is_valid<'fcx, 'tcx>(
         };
 
         let obligation = traits::Obligation::new(
-            cause.clone(),
+            cause,
             fcx.param_env,
             trait_ref.to_predicate()
         );
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 985bb02614b61..20a4f86aedb90 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -317,7 +317,7 @@ pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOpt
         // Ensure that rustdoc works even if rustc is feature-staged
         unstable_features: UnstableFeatures::Allow,
         actually_rustdoc: true,
-        debugging_opts: debugging_options.clone(),
+        debugging_opts: debugging_options,
         error_format,
         edition,
         describe_lints,
diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
index 5bce5d6ba5de1..baf99bacb8ee6 100644
--- a/src/librustdoc/test.rs
+++ b/src/librustdoc/test.rs
@@ -740,7 +740,7 @@ impl Tester for Collector {
         debug!("Creating test {}: {}", name, test);
         self.tests.push(testing::TestDescAndFn {
             desc: testing::TestDesc {
-                name: testing::DynTestName(name.clone()),
+                name: testing::DynTestName(name),
                 ignore: config.ignore,
                 // compiler failures are test failures
                 should_panic: testing::ShouldPanic::No,
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 6b699464ba9a8..22745a1a76d53 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -23,6 +23,7 @@ use log::debug;
 use rustc_data_structures::fx::{FxHashMap};
 use std::borrow::Cow;
 use std::collections::hash_map::Entry;
+use std::slice;
 
 use rustc_data_structures::sync::Lrc;
 use errors::Applicability;
@@ -359,10 +360,10 @@ pub fn compile(
 
     // don't abort iteration early, so that errors for multiple lhses can be reported
     for lhs in &lhses {
-        valid &= check_lhs_no_empty_seq(sess, &[lhs.clone()]);
+        valid &= check_lhs_no_empty_seq(sess, slice::from_ref(lhs));
         valid &= check_lhs_duplicate_matcher_bindings(
             sess,
-            &[lhs.clone()],
+            slice::from_ref(lhs),
             &mut FxHashMap::default(),
             def.id
         );
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 004323301a22a..1d8f68ec63a41 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -557,11 +557,10 @@ declare_features! (
     // Allows the user of associated type bounds.
     (active, associated_type_bounds, "1.34.0", Some(52662), None),
 
-    // Attributes on formal function params
+    // Attributes on formal function params.
     (active, param_attrs, "1.36.0", Some(60406), None),
 
-    // Allows calling constructor functions in `const fn`
-    // FIXME Create issue
+    // Allows calling constructor functions in `const fn`.
     (active, const_constructor, "1.37.0", Some(61456), None),
 
     // #[repr(transparent)] on enums.
diff --git a/src/libsyntax_ext/format.rs b/src/libsyntax_ext/format.rs
index 85b524786b2f5..f44a6e7efa4f1 100644
--- a/src/libsyntax_ext/format.rs
+++ b/src/libsyntax_ext/format.rs
@@ -887,7 +887,7 @@ pub fn expand_preparsed_format_args(ecx: &mut ExtCtxt<'_>,
     };
 
     let fmt_str = &*fmt.node.0.as_str();  // for the suggestions below
-    let mut parser = parse::Parser::new(fmt_str, str_style, skips.clone(), append_newline);
+    let mut parser = parse::Parser::new(fmt_str, str_style, skips, append_newline);
 
     let mut unverified_pieces = Vec::new();
     while let Some(piece) = parser.next() {
diff --git a/src/libsyntax_ext/proc_macro_server.rs b/src/libsyntax_ext/proc_macro_server.rs
index 00a420d3fa899..b5d5a38ce5b38 100644
--- a/src/libsyntax_ext/proc_macro_server.rs
+++ b/src/libsyntax_ext/proc_macro_server.rs
@@ -409,7 +409,7 @@ impl server::TokenStream for Rustc<'_> {
     }
     fn from_str(&mut self, src: &str) -> Self::TokenStream {
         parse::parse_stream_from_source_str(
-            FileName::proc_macro_source_code(src.clone()),
+            FileName::proc_macro_source_code(src),
             src.to_string(),
             self.sess,
             Some(self.call_site),
diff --git a/src/tools/miri b/src/tools/miri
index 965160d4d7976..fd0dccd4b1216 160000
--- a/src/tools/miri
+++ b/src/tools/miri
@@ -1 +1 @@
-Subproject commit 965160d4d7976ddead182b4a65b73f59818537de
+Subproject commit fd0dccd4b12169e0aac42aff8addbb26b6d72197