diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 75c656973f963..4d19be62df809 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -36,6 +36,7 @@ use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{ErrorGuaranteed, Span, DUMMY_SP};
+use std::borrow::Cow;
 use std::cmp;
 use std::fmt;
 use std::mem;
@@ -2272,7 +2273,7 @@ impl std::fmt::Debug for InlineAsmOptions {
 
 #[derive(Clone, PartialEq, Encodable, Decodable, Debug, Hash, HashStable_Generic)]
 pub enum InlineAsmTemplatePiece {
-    String(String),
+    String(Cow<'static, str>),
     Placeholder { operand_idx: usize, modifier: Option<char>, span: Span },
 }
 
diff --git a/compiler/rustc_builtin_macros/src/asm.rs b/compiler/rustc_builtin_macros/src/asm.rs
index dd0f9aaf22104..b8fe6338493d0 100644
--- a/compiler/rustc_builtin_macros/src/asm.rs
+++ b/compiler/rustc_builtin_macros/src/asm.rs
@@ -459,7 +459,7 @@ fn expand_preparsed_asm(
 
     for (i, template_expr) in args.templates.into_iter().enumerate() {
         if i != 0 {
-            template.push(ast::InlineAsmTemplatePiece::String("\n".to_string()));
+            template.push(ast::InlineAsmTemplatePiece::String("\n".into()));
         }
 
         let msg = "asm template must be a string literal";
@@ -527,7 +527,7 @@ fn expand_preparsed_asm(
 
         // Don't treat raw asm as a format string.
         if args.options.contains(ast::InlineAsmOptions::RAW) {
-            template.push(ast::InlineAsmTemplatePiece::String(template_str.to_string()));
+            template.push(ast::InlineAsmTemplatePiece::String(template_str.to_string().into()));
             let template_num_lines = 1 + template_str.matches('\n').count();
             line_spans.extend(std::iter::repeat(template_sp).take(template_num_lines));
             continue;
@@ -577,7 +577,7 @@ fn expand_preparsed_asm(
         for piece in unverified_pieces {
             match piece {
                 parse::Piece::String(s) => {
-                    template.push(ast::InlineAsmTemplatePiece::String(s.to_string()))
+                    template.push(ast::InlineAsmTemplatePiece::String(s.to_string().into()))
                 }
                 parse::Piece::NextArgument(arg) => {
                     let span = arg_spans.next().unwrap_or(template_sp);
diff --git a/compiler/rustc_codegen_cranelift/src/inline_asm.rs b/compiler/rustc_codegen_cranelift/src/inline_asm.rs
index c88230c936056..16edec47e1029 100644
--- a/compiler/rustc_codegen_cranelift/src/inline_asm.rs
+++ b/compiler/rustc_codegen_cranelift/src/inline_asm.rs
@@ -46,9 +46,7 @@ pub(crate) fn codegen_inline_asm_terminator<'tcx>(
     // Used by panic_abort on Windows, but uses a syntax which only happens to work with
     // asm!() by accident and breaks with the GNU assembler as well as global_asm!() for
     // the LLVM backend.
-    if template.len() == 1
-        && template[0] == InlineAsmTemplatePiece::String("int $$0x29".to_string())
-    {
+    if template.len() == 1 && template[0] == InlineAsmTemplatePiece::String("int $$0x29".into()) {
         fx.bcx.ins().trap(TrapCode::User(1));
         return;
     }
diff --git a/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs b/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs
index e1896138e487b..b7c20098489e9 100644
--- a/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs
+++ b/compiler/rustc_codegen_cranelift/src/intrinsics/llvm_x86.rs
@@ -40,7 +40,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
                     shl rdx, 32
                     or rax, rdx
                     "
-                    .to_string(),
+                    .into(),
                 )],
                 &[
                     CInlineAsmOperand::In {
@@ -471,7 +471,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
             // into 0x80000000 for which Cranelift doesn't have a native instruction.
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(format!("cvtps2dq xmm0, xmm0"))],
+                &[InlineAsmTemplatePiece::String("cvtps2dq xmm0, xmm0".into())],
                 &[CInlineAsmOperand::InOut {
                     reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
                     _late: true,
@@ -875,7 +875,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(asm.to_string())],
+                &[InlineAsmTemplatePiece::String(asm.into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::ax)),
@@ -914,7 +914,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(format!("pcmpestri xmm0, xmm1, {imm8}"))],
+                &[InlineAsmTemplatePiece::String(format!("pcmpestri xmm0, xmm1, {imm8}").into())],
                 &[
                     CInlineAsmOperand::In {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
@@ -967,7 +967,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(format!("pcmpestrm xmm0, xmm1, {imm8}"))],
+                &[InlineAsmTemplatePiece::String(format!("pcmpestrm xmm0, xmm1, {imm8}").into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
@@ -1015,7 +1015,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(format!("pclmulqdq xmm0, xmm1, {imm8}"))],
+                &[InlineAsmTemplatePiece::String(format!("pclmulqdq xmm0, xmm1, {imm8}").into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
@@ -1052,7 +1052,9 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(format!("aeskeygenassist xmm0, xmm0, {imm8}"))],
+                &[InlineAsmTemplatePiece::String(
+                    format!("aeskeygenassist xmm0, xmm0, {imm8}").into(),
+                )],
                 &[CInlineAsmOperand::InOut {
                     reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
                     _late: true,
@@ -1071,7 +1073,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("aesimc xmm0, xmm0".to_string())],
+                &[InlineAsmTemplatePiece::String("aesimc xmm0, xmm0".into())],
                 &[CInlineAsmOperand::InOut {
                     reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
                     _late: true,
@@ -1091,7 +1093,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("aesenc xmm0, xmm1".to_string())],
+                &[InlineAsmTemplatePiece::String("aesenc xmm0, xmm1".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
@@ -1117,7 +1119,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("aesenclast xmm0, xmm1".to_string())],
+                &[InlineAsmTemplatePiece::String("aesenclast xmm0, xmm1".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
@@ -1143,7 +1145,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("aesdec xmm0, xmm1".to_string())],
+                &[InlineAsmTemplatePiece::String("aesdec xmm0, xmm1".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
@@ -1169,7 +1171,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("aesdeclast xmm0, xmm1".to_string())],
+                &[InlineAsmTemplatePiece::String("aesdeclast xmm0, xmm1".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm0)),
@@ -1207,7 +1209,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String(format!("sha1rnds4 xmm1, xmm2, {func}"))],
+                &[InlineAsmTemplatePiece::String(format!("sha1rnds4 xmm1, xmm2, {func}").into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm1)),
@@ -1233,7 +1235,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("sha1msg1 xmm1, xmm2".to_string())],
+                &[InlineAsmTemplatePiece::String("sha1msg1 xmm1, xmm2".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm1)),
@@ -1259,7 +1261,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("sha1msg2 xmm1, xmm2".to_string())],
+                &[InlineAsmTemplatePiece::String("sha1msg2 xmm1, xmm2".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm1)),
@@ -1285,7 +1287,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("sha1nexte xmm1, xmm2".to_string())],
+                &[InlineAsmTemplatePiece::String("sha1nexte xmm1, xmm2".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm1)),
@@ -1312,7 +1314,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("sha256rnds2 xmm1, xmm2".to_string())],
+                &[InlineAsmTemplatePiece::String("sha256rnds2 xmm1, xmm2".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm1)),
@@ -1343,7 +1345,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("sha256msg1 xmm1, xmm2".to_string())],
+                &[InlineAsmTemplatePiece::String("sha256msg1 xmm1, xmm2".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm1)),
@@ -1369,7 +1371,7 @@ pub(crate) fn codegen_x86_llvm_intrinsic_call<'tcx>(
 
             codegen_inline_asm_inner(
                 fx,
-                &[InlineAsmTemplatePiece::String("sha256msg2 xmm1, xmm2".to_string())],
+                &[InlineAsmTemplatePiece::String("sha256msg2 xmm1, xmm2".into())],
                 &[
                     CInlineAsmOperand::InOut {
                         reg: InlineAsmRegOrRegClass::Reg(InlineAsmReg::X86(X86InlineAsmReg::xmm1)),