diff --git a/compiler/rustc_codegen_ssa/src/glue.rs b/compiler/rustc_codegen_ssa/src/glue.rs
index 694f5434e9afd..a63a547d8c938 100644
--- a/compiler/rustc_codegen_ssa/src/glue.rs
+++ b/compiler/rustc_codegen_ssa/src/glue.rs
@@ -5,7 +5,7 @@
 use crate::common::IntPredicate;
 use crate::meth;
 use crate::traits::*;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, UintTy};
 use rustc_target::abi::WrappingRange;
 
 pub fn size_and_align_of_dst<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
@@ -38,8 +38,15 @@ pub fn size_and_align_of_dst<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
             let unit = layout.field(bx, 0);
             // The info in this case is the length of the str, so the size is that
             // times the unit size.
+            let (size, overflow) = bx.checked_binop(
+                OverflowOp::Mul,
+                bx.tcx().mk_mach_uint(UintTy::Usize),
+                bx.const_usize(unit.size.bytes()),
+                info.unwrap(),
+            );
+            let ptr_max = bx.data_layout().pointer_size.truncate(u128::MAX) as u64;
             (
-                bx.mul(info.unwrap(), bx.const_usize(unit.size.bytes())),
+                bx.select(overflow, bx.const_usize(ptr_max), size),
                 bx.const_usize(unit.align.abi.bytes()),
             )
         }