diff --git a/build_sysroot/Cargo.toml b/build_sysroot/Cargo.toml
index 648a407984c..45484027edc 100644
--- a/build_sysroot/Cargo.toml
+++ b/build_sysroot/Cargo.toml
@@ -18,3 +18,7 @@ compiler_builtins = { path = "./compiler_builtins" }
 
 [profile.release]
 debug = true
+
+[profile.dev]
+# FIXME correctly align constants, so that copy_nonoverlapping doesn't complain about alignment
+debug-assertions = false
diff --git a/patches/0001-Disable-stdsimd.patch b/patches/0001-Disable-stdsimd.patch
index 343b618be73..7fb003d199e 100644
--- a/patches/0001-Disable-stdsimd.patch
+++ b/patches/0001-Disable-stdsimd.patch
@@ -18,7 +18,7 @@ index f2165c6..cdb42c1 100644
  
 +/*
  // Pull in the `core_arch` crate directly into libcore. The contents of
- // `core_arch` are in a different repository: rust-lang-nursery/stdsimd.
+ // `core_arch` are in a different repository: rust-lang/stdarch.
  //
 @@ -235,3 +236,4 @@ mod core_arch;
  
@@ -53,7 +53,7 @@ index 6dd3a6c..c7401e2 100644
  
 +/*
  // Pull in the `std_detect` crate directly into libstd. The contents of
- // `std_detect` are in a different repository: rust-lang-nursery/stdsimd.
+ // `std_detect` are in a different repository: rust-lang/stdarch.
  //
 @@ -505,6 +502,7 @@ mod std_detect;
  #[unstable(feature = "stdsimd", issue = "48556")]
diff --git a/src/unsize.rs b/src/unsize.rs
index 57399e10b7a..8f8f9116f59 100644
--- a/src/unsize.rs
+++ b/src/unsize.rs
@@ -14,7 +14,8 @@ pub fn unsized_info<'a, 'tcx: 'a>(
     target: Ty<'tcx>,
     old_info: Option<Value>,
 ) -> Value {
-    let (source, target) = fx.tcx.struct_lockstep_tails(source, target);
+    let (source, target) =
+        fx.tcx.struct_lockstep_tails_erasing_lifetimes(source, target, ParamEnv::reveal_all());
     match (&source.sty, &target.sty) {
         (&ty::Array(_, len), &ty::Slice(_)) => fx
             .bcx