diff --git a/rust-version b/rust-version
index a54e33ae52..e23293ea55 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-79d246112dc95bbd67848f7546f3fd1aca516b82
+4d4bb491b65c300835442f6cb4f34fc9a5685c26
diff --git a/src/bin/miri.rs b/src/bin/miri.rs
index 22108df0f2..6955e649b4 100644
--- a/src/bin/miri.rs
+++ b/src/bin/miri.rs
@@ -341,6 +341,9 @@ fn main() {
     // (`install_ice_hook` might change `RUST_BACKTRACE`.)
     let env_snapshot = env::vars_os().collect::<Vec<_>>();
 
+    let args = rustc_driver::args::raw_args(&early_dcx)
+        .unwrap_or_else(|_| std::process::exit(rustc_driver::EXIT_FAILURE));
+
     // If the environment asks us to actually be rustc, then do that.
     if let Some(crate_kind) = env::var_os("MIRI_BE_RUSTC") {
         // Earliest rustc setup.
@@ -358,7 +361,7 @@ fn main() {
 
         // We cannot use `rustc_driver::main` as we need to adjust the CLI arguments.
         run_compiler(
-            env::args().collect(),
+            args,
             target_crate,
             &mut MiriBeRustCompilerCalls { target_crate },
             using_internal_features,
@@ -381,7 +384,7 @@ fn main() {
 
     // If user has explicitly enabled/disabled isolation
     let mut isolation_enabled: Option<bool> = None;
-    for arg in env::args() {
+    for arg in args {
         if rustc_args.is_empty() {
             // Very first arg: binary name.
             rustc_args.push(arg);
diff --git a/src/machine.rs b/src/machine.rs
index 490fa6f553..f0e3c43a5c 100644
--- a/src/machine.rs
+++ b/src/machine.rs
@@ -8,7 +8,6 @@ use std::fmt;
 use std::path::Path;
 use std::process;
 
-use either::Either;
 use rand::rngs::StdRng;
 use rand::Rng;
 use rand::SeedableRng;
@@ -957,7 +956,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
             // to run extra MIR), and Ok(Some(body)) if we found MIR to run for the
             // foreign function
             // Any needed call to `goto_block` will be performed by `emulate_foreign_item`.
-            let args = ecx.copy_fn_args(args)?; // FIXME: Should `InPlace` arguments be reset to uninit?
+            let args = ecx.copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
             let link_name = ecx.item_link_name(instance.def_id());
             return ecx.emulate_foreign_item(link_name, abi, &args, dest, ret, unwind);
         }
@@ -976,7 +975,7 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
         ret: Option<mir::BasicBlock>,
         unwind: mir::UnwindAction,
     ) -> InterpResult<'tcx> {
-        let args = ecx.copy_fn_args(args)?; // FIXME: Should `InPlace` arguments be reset to uninit?
+        let args = ecx.copy_fn_args(args); // FIXME: Should `InPlace` arguments be reset to uninit?
         ecx.emulate_dyn_sym(fn_val, abi, &args, dest, ret, unwind)
     }
 
@@ -1329,18 +1328,12 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
 
     fn protect_in_place_function_argument(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        place: &PlaceTy<'tcx, Provenance>,
+        place: &MPlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx> {
         // If we have a borrow tracker, we also have it set up protection so that all reads *and
         // writes* during this call are insta-UB.
         let protected_place = if ecx.machine.borrow_tracker.is_some() {
-            // Have to do `to_op` first because a `Place::Local` doesn't imply the local doesn't have an address.
-            if let Either::Left(place) = ecx.place_to_op(place)?.as_mplace_or_imm() {
-                ecx.protect_place(&place)?.into()
-            } else {
-                // Locals that don't have their address taken are as protected as they can ever be.
-                place.clone()
-            }
+            ecx.protect_place(place)?
         } else {
             // No borrow tracker.
             place.clone()