diff --git a/cranelift/codegen/src/abi.rs b/cranelift/codegen/src/abi.rs
index 4c0b8d4dbc..8564fd5a24 100644
--- a/cranelift/codegen/src/abi.rs
+++ b/cranelift/codegen/src/abi.rs
@@ -5,7 +5,7 @@
 
 use crate::ir::{AbiParam, ArgumentExtension, ArgumentLoc, Type};
 use core::cmp::Ordering;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Legalization action to perform on a single argument or return value when converting a
 /// signature.
diff --git a/cranelift/codegen/src/binemit/relaxation.rs b/cranelift/codegen/src/binemit/relaxation.rs
index 43f361885a..806129e9af 100644
--- a/cranelift/codegen/src/binemit/relaxation.rs
+++ b/cranelift/codegen/src/binemit/relaxation.rs
@@ -227,7 +227,7 @@ fn try_fold_redundant_jump(
     }
 
     // Build a value list of first_args (unchanged) followed by second_params (rewritten).
-    let arguments_vec: std::vec::Vec<_> = first_args
+    let arguments_vec: alloc::vec::Vec<_> = first_args
         .iter()
         .chain(second_params.iter())
         .map(|x| *x)
diff --git a/cranelift/codegen/src/binemit/stackmap.rs b/cranelift/codegen/src/binemit/stackmap.rs
index 5d6844dcf3..4d513f7322 100644
--- a/cranelift/codegen/src/binemit/stackmap.rs
+++ b/cranelift/codegen/src/binemit/stackmap.rs
@@ -1,7 +1,7 @@
 use crate::bitset::BitSet;
 use crate::ir;
 use crate::isa::TargetIsa;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 type Num = u32;
 const NUM_BITS: usize = core::mem::size_of::<Num>() * 8;
@@ -42,7 +42,7 @@ impl Stackmap {
         let frame_size = stack.frame_size.unwrap();
         let word_size = ir::stackslot::StackSize::from(isa.pointer_bytes());
         let num_words = (frame_size / word_size) as usize;
-        let mut vec = std::vec::Vec::with_capacity(num_words);
+        let mut vec = alloc::vec::Vec::with_capacity(num_words);
 
         vec.resize(num_words, false);
 
diff --git a/cranelift/codegen/src/cfg_printer.rs b/cranelift/codegen/src/cfg_printer.rs
index e3c62820cd..c67e8b1eec 100644
--- a/cranelift/codegen/src/cfg_printer.rs
+++ b/cranelift/codegen/src/cfg_printer.rs
@@ -1,7 +1,7 @@
 //! The `CFGPrinter` utility.
 
 use core::fmt::{Display, Formatter, Result, Write};
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 use crate::entity::SecondaryMap;
 use crate::flowgraph::{BasicBlock, ControlFlowGraph};
diff --git a/cranelift/codegen/src/context.rs b/cranelift/codegen/src/context.rs
index 8bbe2893de..aad08a5481 100644
--- a/cranelift/codegen/src/context.rs
+++ b/cranelift/codegen/src/context.rs
@@ -34,7 +34,7 @@ use crate::unreachable_code::eliminate_unreachable_code;
 use crate::value_label::{build_value_labels_ranges, ComparableSourceLoc, ValueLabelsRanges};
 use crate::verifier::{verify_context, verify_locations, VerifierErrors, VerifierResult};
 use log::debug;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Persistent data structures and compilation pipeline.
 pub struct Context {
diff --git a/cranelift/codegen/src/dominator_tree.rs b/cranelift/codegen/src/dominator_tree.rs
index 8191c310eb..737019d315 100644
--- a/cranelift/codegen/src/dominator_tree.rs
+++ b/cranelift/codegen/src/dominator_tree.rs
@@ -9,7 +9,7 @@ use crate::timing;
 use core::cmp;
 use core::cmp::Ordering;
 use core::mem;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// RPO numbers are not first assigned in a contiguous way but as multiples of STRIDE, to leave
 /// room for modifications of the dominator tree.
diff --git a/cranelift/codegen/src/flowgraph.rs b/cranelift/codegen/src/flowgraph.rs
index 645b7d4fff..f53cfa6bff 100644
--- a/cranelift/codegen/src/flowgraph.rs
+++ b/cranelift/codegen/src/flowgraph.rs
@@ -214,7 +214,7 @@ mod tests {
     use super::*;
     use crate::cursor::{Cursor, FuncCursor};
     use crate::ir::{types, Function, InstBuilder};
-    use std::vec::Vec;
+    use alloc::vec::Vec;
 
     #[test]
     fn empty() {
diff --git a/cranelift/codegen/src/ir/constant.rs b/cranelift/codegen/src/ir/constant.rs
index 9f21209c4c..c4d7cb0898 100644
--- a/cranelift/codegen/src/ir/constant.rs
+++ b/cranelift/codegen/src/ir/constant.rs
@@ -11,8 +11,8 @@
 use crate::ir::Constant;
 use crate::HashMap;
 use cranelift_entity::EntityRef;
-use std::collections::BTreeMap;
-use std::vec::Vec;
+use alloc::collections::BTreeMap;
+use alloc::vec::Vec;
 
 /// This type describes the actual constant data.
 pub type ConstantData = Vec<u8>;
diff --git a/cranelift/codegen/src/ir/dfg.rs b/cranelift/codegen/src/ir/dfg.rs
index e4ec9c6be8..34ed10622d 100644
--- a/cranelift/codegen/src/ir/dfg.rs
+++ b/cranelift/codegen/src/ir/dfg.rs
@@ -19,7 +19,7 @@ use core::iter;
 use core::mem;
 use core::ops::{Index, IndexMut};
 use core::u16;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// A data flow graph defines all instructions and extended basic blocks in a function as well as
 /// the data flow dependencies between them. The DFG also tracks values which can be either
@@ -1093,7 +1093,7 @@ mod tests {
     use crate::cursor::{Cursor, FuncCursor};
     use crate::ir::types;
     use crate::ir::{Function, InstructionData, Opcode, TrapCode};
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn make_inst() {
diff --git a/cranelift/codegen/src/ir/entities.rs b/cranelift/codegen/src/ir/entities.rs
index 1f8e1fc6a2..552a9f3ae0 100644
--- a/cranelift/codegen/src/ir/entities.rs
+++ b/cranelift/codegen/src/ir/entities.rs
@@ -456,7 +456,7 @@ impl From<Table> for AnyEntity {
 mod tests {
     use super::*;
     use core::u32;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn value_with_number() {
diff --git a/cranelift/codegen/src/ir/extfunc.rs b/cranelift/codegen/src/ir/extfunc.rs
index 0b74fd3d24..f09b428833 100644
--- a/cranelift/codegen/src/ir/extfunc.rs
+++ b/cranelift/codegen/src/ir/extfunc.rs
@@ -9,7 +9,7 @@ use crate::ir::{ArgumentLoc, ExternalName, SigRef, Type};
 use crate::isa::{CallConv, RegInfo, RegUnit};
 use core::fmt;
 use core::str::FromStr;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Function signature.
 ///
@@ -335,7 +335,7 @@ impl fmt::Display for ExtFuncData {
 mod tests {
     use super::*;
     use crate::ir::types::{B8, F32, I32};
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn argument_type() {
diff --git a/cranelift/codegen/src/ir/extname.rs b/cranelift/codegen/src/ir/extname.rs
index 5fd8600882..d153db9cbd 100644
--- a/cranelift/codegen/src/ir/extname.rs
+++ b/cranelift/codegen/src/ir/extname.rs
@@ -121,7 +121,7 @@ mod tests {
     use super::ExternalName;
     use crate::ir::LibCall;
     use core::u32;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn display_testcase() {
diff --git a/cranelift/codegen/src/ir/immediates.rs b/cranelift/codegen/src/ir/immediates.rs
index eb6dfad34b..5d3807671f 100644
--- a/cranelift/codegen/src/ir/immediates.rs
+++ b/cranelift/codegen/src/ir/immediates.rs
@@ -8,7 +8,7 @@ use core::fmt::{self, Display, Formatter};
 use core::iter::FromIterator;
 use core::str::{from_utf8, FromStr};
 use core::{i32, u32};
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Convert a type into a vector of bytes; all implementors in this file must use little-endian
 /// orderings of bytes to match WebAssembly's little-endianness.
@@ -940,7 +940,7 @@ mod tests {
     use core::mem;
     use core::str::FromStr;
     use core::{f32, f64};
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn format_imm64() {
diff --git a/cranelift/codegen/src/ir/instructions.rs b/cranelift/codegen/src/ir/instructions.rs
index b3c3d0d211..97c84110aa 100644
--- a/cranelift/codegen/src/ir/instructions.rs
+++ b/cranelift/codegen/src/ir/instructions.rs
@@ -9,7 +9,7 @@
 use core::fmt::{self, Display, Formatter};
 use core::ops::{Deref, DerefMut};
 use core::str::FromStr;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 use crate::ir;
 use crate::ir::types;
@@ -560,7 +560,7 @@ pub enum ResolvedConstraint {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn opcodes() {
diff --git a/cranelift/codegen/src/ir/jumptable.rs b/cranelift/codegen/src/ir/jumptable.rs
index a40ee48e74..596e668e89 100644
--- a/cranelift/codegen/src/ir/jumptable.rs
+++ b/cranelift/codegen/src/ir/jumptable.rs
@@ -6,7 +6,7 @@
 use crate::ir::entities::Ebb;
 use core::fmt::{self, Display, Formatter};
 use core::slice::{Iter, IterMut};
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Contents of a jump table.
 ///
@@ -85,7 +85,7 @@ mod tests {
     use super::JumpTableData;
     use crate::entity::EntityRef;
     use crate::ir::Ebb;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn empty() {
diff --git a/cranelift/codegen/src/ir/layout.rs b/cranelift/codegen/src/ir/layout.rs
index 632c03dc59..3d1f5e975c 100644
--- a/cranelift/codegen/src/ir/layout.rs
+++ b/cranelift/codegen/src/ir/layout.rs
@@ -751,7 +751,7 @@ mod tests {
     use crate::entity::EntityRef;
     use crate::ir::{Ebb, Inst, ProgramOrder, SourceLoc};
     use core::cmp::Ordering;
-    use std::vec::Vec;
+    use alloc::vec::Vec;
 
     struct LayoutCursor<'f> {
         /// Borrowed function layout. Public so it can be re-borrowed from this cursor.
diff --git a/cranelift/codegen/src/ir/libcall.rs b/cranelift/codegen/src/ir/libcall.rs
index 1e19891221..52c4c40dad 100644
--- a/cranelift/codegen/src/ir/libcall.rs
+++ b/cranelift/codegen/src/ir/libcall.rs
@@ -209,7 +209,7 @@ fn make_funcref(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn display() {
diff --git a/cranelift/codegen/src/ir/mod.rs b/cranelift/codegen/src/ir/mod.rs
index 9c03d569db..8b89227ff2 100644
--- a/cranelift/codegen/src/ir/mod.rs
+++ b/cranelift/codegen/src/ir/mod.rs
@@ -100,7 +100,7 @@ pub struct ValueLabelStart {
 #[derive(Debug, Clone)]
 pub enum ValueLabelAssignments {
     /// Original value labels assigned at transform.
-    Starts(std::vec::Vec<ValueLabelStart>),
+    Starts(alloc::vec::Vec<ValueLabelStart>),
 
     /// A value alias to original value.
     Alias {
diff --git a/cranelift/codegen/src/ir/progpoint.rs b/cranelift/codegen/src/ir/progpoint.rs
index bd03c120cd..32c349aa00 100644
--- a/cranelift/codegen/src/ir/progpoint.rs
+++ b/cranelift/codegen/src/ir/progpoint.rs
@@ -148,7 +148,7 @@ mod tests {
     use super::*;
     use crate::entity::EntityRef;
     use crate::ir::{Ebb, Inst};
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn convert() {
diff --git a/cranelift/codegen/src/ir/sourceloc.rs b/cranelift/codegen/src/ir/sourceloc.rs
index a0d051d3aa..b8f162366f 100644
--- a/cranelift/codegen/src/ir/sourceloc.rs
+++ b/cranelift/codegen/src/ir/sourceloc.rs
@@ -54,7 +54,7 @@ impl fmt::Display for SourceLoc {
 #[cfg(test)]
 mod tests {
     use crate::ir::SourceLoc;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn display() {
diff --git a/cranelift/codegen/src/ir/stackslot.rs b/cranelift/codegen/src/ir/stackslot.rs
index 0b488582d4..fb526ab50e 100644
--- a/cranelift/codegen/src/ir/stackslot.rs
+++ b/cranelift/codegen/src/ir/stackslot.rs
@@ -11,7 +11,7 @@ use core::fmt;
 use core::ops::{Index, IndexMut};
 use core::slice;
 use core::str::FromStr;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 #[cfg(feature = "enable-serde")]
 use serde::{Deserialize, Serialize};
@@ -343,7 +343,7 @@ mod tests {
     use super::*;
     use crate::ir::types;
     use crate::ir::Function;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn stack_slot() {
diff --git a/cranelift/codegen/src/ir/trapcode.rs b/cranelift/codegen/src/ir/trapcode.rs
index 5621e1d91c..3f8ffe3fb5 100644
--- a/cranelift/codegen/src/ir/trapcode.rs
+++ b/cranelift/codegen/src/ir/trapcode.rs
@@ -103,7 +103,7 @@ impl FromStr for TrapCode {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     // Everything but user-defined codes.
     const CODES: [TrapCode; 11] = [
diff --git a/cranelift/codegen/src/ir/types.rs b/cranelift/codegen/src/ir/types.rs
index 10fca8aaa8..4ada74b070 100644
--- a/cranelift/codegen/src/ir/types.rs
+++ b/cranelift/codegen/src/ir/types.rs
@@ -363,7 +363,7 @@ impl Default for Type {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn basic_scalars() {
diff --git a/cranelift/codegen/src/isa/arm32/mod.rs b/cranelift/codegen/src/isa/arm32/mod.rs
index ed5854593b..f377560581 100644
--- a/cranelift/codegen/src/isa/arm32/mod.rs
+++ b/cranelift/codegen/src/isa/arm32/mod.rs
@@ -16,7 +16,7 @@ use crate::isa::Builder as IsaBuilder;
 use crate::isa::{EncInfo, RegClass, RegInfo, TargetIsa};
 use crate::regalloc;
 use core::fmt;
-use std::boxed::Box;
+use alloc::boxed::Box;
 use target_lexicon::{Architecture, Triple};
 
 #[allow(dead_code)]
diff --git a/cranelift/codegen/src/isa/arm32/registers.rs b/cranelift/codegen/src/isa/arm32/registers.rs
index 70549528cf..df555b4043 100644
--- a/cranelift/codegen/src/isa/arm32/registers.rs
+++ b/cranelift/codegen/src/isa/arm32/registers.rs
@@ -8,7 +8,7 @@ include!(concat!(env!("OUT_DIR"), "/registers-arm32.rs"));
 mod tests {
     use super::{D, GPR, INFO, S};
     use crate::isa::RegUnit;
-    use std::string::{String, ToString};
+    use alloc::string::{String, ToString};
 
     #[test]
     fn unit_encodings() {
diff --git a/cranelift/codegen/src/isa/arm64/mod.rs b/cranelift/codegen/src/isa/arm64/mod.rs
index 71ae93c0fe..84afc33cbd 100644
--- a/cranelift/codegen/src/isa/arm64/mod.rs
+++ b/cranelift/codegen/src/isa/arm64/mod.rs
@@ -16,7 +16,7 @@ use crate::isa::Builder as IsaBuilder;
 use crate::isa::{EncInfo, RegClass, RegInfo, TargetIsa};
 use crate::regalloc;
 use core::fmt;
-use std::boxed::Box;
+use alloc::boxed::Box;
 use target_lexicon::Triple;
 
 #[allow(dead_code)]
diff --git a/cranelift/codegen/src/isa/arm64/registers.rs b/cranelift/codegen/src/isa/arm64/registers.rs
index 91ca256bbe..c02f6b7d4d 100644
--- a/cranelift/codegen/src/isa/arm64/registers.rs
+++ b/cranelift/codegen/src/isa/arm64/registers.rs
@@ -8,7 +8,7 @@ include!(concat!(env!("OUT_DIR"), "/registers-arm64.rs"));
 mod tests {
     use super::INFO;
     use crate::isa::RegUnit;
-    use std::string::{String, ToString};
+    use alloc::string::{String, ToString};
 
     #[test]
     fn unit_encodings() {
diff --git a/cranelift/codegen/src/isa/mod.rs b/cranelift/codegen/src/isa/mod.rs
index 6457eb9ad7..8c6b3bc203 100644
--- a/cranelift/codegen/src/isa/mod.rs
+++ b/cranelift/codegen/src/isa/mod.rs
@@ -25,7 +25,7 @@
 //! # fn main() {
 //! use cranelift_codegen::isa;
 //! use cranelift_codegen::settings::{self, Configurable};
-//! use std::str::FromStr;
+//! use alloc::str::FromStr;
 //! use target_lexicon::Triple;
 //!
 //! let shared_builder = settings::builder();
@@ -65,7 +65,7 @@ use crate::settings::SetResult;
 use crate::timing;
 use core::fmt;
 use failure_derive::Fail;
-use std::boxed::Box;
+use alloc::boxed::Box;
 use target_lexicon::{triple, Architecture, PointerWidth, Triple};
 
 #[cfg(feature = "riscv")]
@@ -119,7 +119,7 @@ pub fn lookup(triple: Triple) -> Result<Builder, LookupError> {
 /// Look for a supported ISA with the given `name`.
 /// Return a builder that can create a corresponding `TargetIsa`.
 pub fn lookup_by_name(name: &str) -> Result<Builder, LookupError> {
-    use std::str::FromStr;
+    use alloc::str::FromStr;
     lookup(triple!(name))
 }
 
diff --git a/cranelift/codegen/src/isa/riscv/mod.rs b/cranelift/codegen/src/isa/riscv/mod.rs
index 93ef3787f0..e4bd6c9bbd 100644
--- a/cranelift/codegen/src/isa/riscv/mod.rs
+++ b/cranelift/codegen/src/isa/riscv/mod.rs
@@ -16,7 +16,7 @@ use crate::isa::Builder as IsaBuilder;
 use crate::isa::{EncInfo, RegClass, RegInfo, TargetIsa};
 use crate::regalloc;
 use core::fmt;
-use std::boxed::Box;
+use alloc::boxed::Box;
 use target_lexicon::{PointerWidth, Triple};
 
 #[allow(dead_code)]
@@ -138,7 +138,7 @@ mod tests {
     use crate::isa;
     use crate::settings::{self, Configurable};
     use core::str::FromStr;
-    use std::string::{String, ToString};
+    use alloc::string::{String, ToString};
     use target_lexicon::triple;
 
     fn encstr(isa: &dyn isa::TargetIsa, enc: Result<isa::Encoding, isa::Legalize>) -> String {
diff --git a/cranelift/codegen/src/isa/riscv/registers.rs b/cranelift/codegen/src/isa/riscv/registers.rs
index 4f167bae8f..9043b7f65f 100644
--- a/cranelift/codegen/src/isa/riscv/registers.rs
+++ b/cranelift/codegen/src/isa/riscv/registers.rs
@@ -8,7 +8,7 @@ include!(concat!(env!("OUT_DIR"), "/registers-riscv.rs"));
 mod tests {
     use super::{FPR, GPR, INFO};
     use crate::isa::RegUnit;
-    use std::string::{String, ToString};
+    use alloc::string::{String, ToString};
 
     #[test]
     fn unit_encodings() {
diff --git a/cranelift/codegen/src/isa/riscv/settings.rs b/cranelift/codegen/src/isa/riscv/settings.rs
index 24c0e2af11..40aa3bed2b 100644
--- a/cranelift/codegen/src/isa/riscv/settings.rs
+++ b/cranelift/codegen/src/isa/riscv/settings.rs
@@ -12,7 +12,7 @@ include!(concat!(env!("OUT_DIR"), "/settings-riscv.rs"));
 mod tests {
     use super::{builder, Flags};
     use crate::settings::{self, Configurable};
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn display_default() {
diff --git a/cranelift/codegen/src/isa/x86/mod.rs b/cranelift/codegen/src/isa/x86/mod.rs
index 8136170cd7..35ca485bd8 100644
--- a/cranelift/codegen/src/isa/x86/mod.rs
+++ b/cranelift/codegen/src/isa/x86/mod.rs
@@ -18,7 +18,7 @@ use crate::regalloc;
 use crate::result::CodegenResult;
 use crate::timing;
 use core::fmt;
-use std::boxed::Box;
+use alloc::boxed::Box;
 use target_lexicon::{PointerWidth, Triple};
 
 #[allow(dead_code)]
diff --git a/cranelift/codegen/src/isa/x86/registers.rs b/cranelift/codegen/src/isa/x86/registers.rs
index a5ebf438d4..130cf41d79 100644
--- a/cranelift/codegen/src/isa/x86/registers.rs
+++ b/cranelift/codegen/src/isa/x86/registers.rs
@@ -8,7 +8,7 @@ include!(concat!(env!("OUT_DIR"), "/registers-x86.rs"));
 mod tests {
     use super::*;
     use crate::isa::RegUnit;
-    use std::string::{String, ToString};
+    use alloc::string::{String, ToString};
 
     #[test]
     fn unit_encodings() {
diff --git a/cranelift/codegen/src/iterators.rs b/cranelift/codegen/src/iterators.rs
index 71cb8cbdf6..ca9c4ab26b 100644
--- a/cranelift/codegen/src/iterators.rs
+++ b/cranelift/codegen/src/iterators.rs
@@ -44,7 +44,7 @@ where
 
 #[cfg(test)]
 mod tests {
-    use std::vec::Vec;
+    use alloc::vec::Vec;
 
     #[test]
     fn adjpairs() {
diff --git a/cranelift/codegen/src/legalizer/boundary.rs b/cranelift/codegen/src/legalizer/boundary.rs
index 8912743dd5..d95d6d4239 100644
--- a/cranelift/codegen/src/legalizer/boundary.rs
+++ b/cranelift/codegen/src/legalizer/boundary.rs
@@ -28,7 +28,7 @@ use crate::ir::{
 use crate::isa::TargetIsa;
 use crate::legalizer::split::{isplit, vsplit};
 use log::debug;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Legalize all the function signatures in `func`.
 ///
diff --git a/cranelift/codegen/src/legalizer/libcall.rs b/cranelift/codegen/src/legalizer/libcall.rs
index 1b11ae7593..b34a90b519 100644
--- a/cranelift/codegen/src/legalizer/libcall.rs
+++ b/cranelift/codegen/src/legalizer/libcall.rs
@@ -4,7 +4,7 @@ use crate::ir;
 use crate::ir::{get_libcall_funcref, InstBuilder};
 use crate::isa::{CallConv, TargetIsa};
 use crate::legalizer::boundary::legalize_libcall_signature;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Try to expand `inst` as a library call, returning true is successful.
 pub fn expand_as_libcall(inst: ir::Inst, func: &mut ir::Function, isa: &dyn TargetIsa) -> bool {
diff --git a/cranelift/codegen/src/legalizer/mod.rs b/cranelift/codegen/src/legalizer/mod.rs
index 2fd353c7b9..f090b14008 100644
--- a/cranelift/codegen/src/legalizer/mod.rs
+++ b/cranelift/codegen/src/legalizer/mod.rs
@@ -21,8 +21,8 @@ use crate::ir::{self, InstBuilder, MemFlags};
 use crate::isa::TargetIsa;
 use crate::predicates;
 use crate::timing;
-use std::collections::BTreeSet;
-use std::vec::Vec;
+use alloc::collections::BTreeSet;
+use alloc::vec::Vec;
 
 mod boundary;
 mod call;
@@ -373,7 +373,7 @@ fn expand_br_table_conds(
     let table_size = func.jump_tables[table].len();
     let mut cond_failed_ebb = vec![];
     if table_size >= 1 {
-        cond_failed_ebb = std::vec::Vec::with_capacity(table_size - 1);
+        cond_failed_ebb = alloc::vec::Vec::with_capacity(table_size - 1);
         for _ in 0..table_size - 1 {
             cond_failed_ebb.push(func.dfg.make_ebb());
         }
diff --git a/cranelift/codegen/src/legalizer/split.rs b/cranelift/codegen/src/legalizer/split.rs
index 5e55419fad..c844fba214 100644
--- a/cranelift/codegen/src/legalizer/split.rs
+++ b/cranelift/codegen/src/legalizer/split.rs
@@ -69,7 +69,7 @@ use crate::flowgraph::{BasicBlock, ControlFlowGraph};
 use crate::ir::{self, Ebb, Inst, InstBuilder, InstructionData, Opcode, Type, Value, ValueDef};
 use core::iter;
 use smallvec::SmallVec;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Split `value` into two values using the `isplit` semantics. Do this by reusing existing values
 /// if possible.
diff --git a/cranelift/codegen/src/lib.rs b/cranelift/codegen/src/lib.rs
index 0e61171d14..ab22e71459 100644
--- a/cranelift/codegen/src/lib.rs
+++ b/cranelift/codegen/src/lib.rs
@@ -35,16 +35,15 @@
         clippy::nonminimal_bool,
         clippy::option_map_unwrap_or,
         clippy::option_map_unwrap_or_else,
-        clippy::print_stdout,
+        clippy::print_allocout,
         clippy::unicode_not_nfc,
         clippy::use_self
     )
 )]
 #![no_std]
 
-#[cfg(not(feature = "std"))]
-#[macro_use]
-extern crate alloc as std;
+extern crate alloc;
+
 #[cfg(feature = "std")]
 #[macro_use]
 extern crate std;
diff --git a/cranelift/codegen/src/licm.rs b/cranelift/codegen/src/licm.rs
index 2866da87d7..284d50c5ea 100644
--- a/cranelift/codegen/src/licm.rs
+++ b/cranelift/codegen/src/licm.rs
@@ -11,7 +11,7 @@ use crate::ir::{
 use crate::isa::TargetIsa;
 use crate::loop_analysis::{Loop, LoopAnalysis};
 use crate::timing;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Performs the LICM pass by detecting loops within the CFG and moving
 /// loop-invariant instructions out of them.
diff --git a/cranelift/codegen/src/loop_analysis.rs b/cranelift/codegen/src/loop_analysis.rs
index ea26332b40..40de9afdff 100644
--- a/cranelift/codegen/src/loop_analysis.rs
+++ b/cranelift/codegen/src/loop_analysis.rs
@@ -9,7 +9,7 @@ use crate::flowgraph::{BasicBlock, ControlFlowGraph};
 use crate::ir::{Ebb, Function, Layout};
 use crate::packed_option::PackedOption;
 use crate::timing;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// A opaque reference to a code loop.
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
@@ -237,7 +237,7 @@ mod tests {
     use crate::flowgraph::ControlFlowGraph;
     use crate::ir::{types, Function, InstBuilder};
     use crate::loop_analysis::{Loop, LoopAnalysis};
-    use std::vec::Vec;
+    use alloc::vec::Vec;
 
     #[test]
     fn nested_loops_detection() {
diff --git a/cranelift/codegen/src/partition_slice.rs b/cranelift/codegen/src/partition_slice.rs
index a4ee129008..959f8c1102 100644
--- a/cranelift/codegen/src/partition_slice.rs
+++ b/cranelift/codegen/src/partition_slice.rs
@@ -53,7 +53,7 @@ where
 #[cfg(test)]
 mod tests {
     use super::partition_slice;
-    use std::vec::Vec;
+    use alloc::vec::Vec;
 
     fn check(x: &[u32], want: &[u32]) {
         assert_eq!(x.len(), want.len());
diff --git a/cranelift/codegen/src/print_errors.rs b/cranelift/codegen/src/print_errors.rs
index a18b5d6955..52169a3880 100644
--- a/cranelift/codegen/src/print_errors.rs
+++ b/cranelift/codegen/src/print_errors.rs
@@ -10,9 +10,9 @@ use crate::verifier::{VerifierError, VerifierErrors};
 use crate::write::{decorate_function, FuncWriter, PlainWriter};
 use core::fmt;
 use core::fmt::Write;
-use std::boxed::Box;
-use std::string::{String, ToString};
-use std::vec::Vec;
+use alloc::boxed::Box;
+use alloc::string::{String, ToString};
+use alloc::vec::Vec;
 
 /// Pretty-print a verifier error.
 pub fn pretty_verifier_error<'a>(
diff --git a/cranelift/codegen/src/redundant_reload_remover.rs b/cranelift/codegen/src/redundant_reload_remover.rs
index 9bcc3fbc9d..a0b6764454 100644
--- a/cranelift/codegen/src/redundant_reload_remover.rs
+++ b/cranelift/codegen/src/redundant_reload_remover.rs
@@ -14,7 +14,7 @@ use crate::isa::{RegInfo, RegUnit, TargetIsa};
 use crate::regalloc::RegDiversions;
 use core::convert::TryInto;
 use cranelift_entity::{PrimaryMap, SecondaryMap};
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 // =============================================================================================
 // A description of the redundant-fill-removal algorithm
diff --git a/cranelift/codegen/src/regalloc/branch_splitting.rs b/cranelift/codegen/src/regalloc/branch_splitting.rs
index a3f118b3d6..3a9e6c87bc 100644
--- a/cranelift/codegen/src/regalloc/branch_splitting.rs
+++ b/cranelift/codegen/src/regalloc/branch_splitting.rs
@@ -4,7 +4,7 @@
 //! between a conditional branch and the following terminator.
 #![cfg(feature = "basic-blocks")]
 
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 use crate::cursor::{Cursor, EncCursor};
 use crate::dominator_tree::DominatorTree;
diff --git a/cranelift/codegen/src/regalloc/coalescing.rs b/cranelift/codegen/src/regalloc/coalescing.rs
index b27a105d65..11846ff45b 100644
--- a/cranelift/codegen/src/regalloc/coalescing.rs
+++ b/cranelift/codegen/src/regalloc/coalescing.rs
@@ -22,7 +22,7 @@ use core::fmt;
 use core::iter;
 use core::slice;
 use log::debug;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 // # Implementation
 //
diff --git a/cranelift/codegen/src/regalloc/live_value_tracker.rs b/cranelift/codegen/src/regalloc/live_value_tracker.rs
index 5e17bb3557..7faed970a7 100644
--- a/cranelift/codegen/src/regalloc/live_value_tracker.rs
+++ b/cranelift/codegen/src/regalloc/live_value_tracker.rs
@@ -12,7 +12,7 @@ use crate::partition_slice::partition_slice;
 use crate::regalloc::affinity::Affinity;
 use crate::regalloc::liveness::Liveness;
 use crate::regalloc::liverange::LiveRange;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 type ValueList = EntityList<Value>;
 
diff --git a/cranelift/codegen/src/regalloc/liveness.rs b/cranelift/codegen/src/regalloc/liveness.rs
index 419e35bc98..ba7ce60459 100644
--- a/cranelift/codegen/src/regalloc/liveness.rs
+++ b/cranelift/codegen/src/regalloc/liveness.rs
@@ -185,7 +185,7 @@ use crate::regalloc::liverange::LiveRange;
 use crate::timing;
 use core::mem;
 use core::ops::Index;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// A set of live ranges, indexed by value number.
 type LiveRangeSet = SparseMap<Value, LiveRange>;
diff --git a/cranelift/codegen/src/regalloc/liverange.rs b/cranelift/codegen/src/regalloc/liverange.rs
index 1d30650fa1..5ababa53b4 100644
--- a/cranelift/codegen/src/regalloc/liverange.rs
+++ b/cranelift/codegen/src/regalloc/liverange.rs
@@ -477,7 +477,7 @@ mod tests {
     use crate::ir::{Ebb, Inst, Value};
     use crate::ir::{ExpandedProgramPoint, ProgramOrder};
     use core::cmp::Ordering;
-    use std::vec::Vec;
+    use alloc::vec::Vec;
 
     // Dummy program order which simply compares indexes.
     // It is assumed that EBBs have indexes that are multiples of 10, and instructions have indexes
diff --git a/cranelift/codegen/src/regalloc/pressure.rs b/cranelift/codegen/src/regalloc/pressure.rs
index 3b15a1c6e2..2cac3bd804 100644
--- a/cranelift/codegen/src/regalloc/pressure.rs
+++ b/cranelift/codegen/src/regalloc/pressure.rs
@@ -277,7 +277,7 @@ mod tests {
     use crate::regalloc::RegisterSet;
     use core::borrow::Borrow;
     use core::str::FromStr;
-    use std::boxed::Box;
+    use alloc::boxed::Box;
     use target_lexicon::triple;
 
     // Make an arm32 `TargetIsa`, if possible.
diff --git a/cranelift/codegen/src/regalloc/register_set.rs b/cranelift/codegen/src/regalloc/register_set.rs
index e5edaa96d6..52b8a6fa0a 100644
--- a/cranelift/codegen/src/regalloc/register_set.rs
+++ b/cranelift/codegen/src/regalloc/register_set.rs
@@ -255,7 +255,7 @@ impl fmt::Display for RegisterSet {
 mod tests {
     use super::*;
     use crate::isa::registers::{RegClass, RegClassData};
-    use std::vec::Vec;
+    use alloc::vec::Vec;
 
     // Register classes for testing.
     const GPR: RegClass = &RegClassData {
diff --git a/cranelift/codegen/src/regalloc/reload.rs b/cranelift/codegen/src/regalloc/reload.rs
index bbc198c45d..ed04e4fc64 100644
--- a/cranelift/codegen/src/regalloc/reload.rs
+++ b/cranelift/codegen/src/regalloc/reload.rs
@@ -22,7 +22,7 @@ use crate::regalloc::liveness::Liveness;
 use crate::timing;
 use crate::topo_order::TopoOrder;
 use log::debug;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Reusable data structures for the reload pass.
 pub struct Reload {
diff --git a/cranelift/codegen/src/regalloc/safepoint.rs b/cranelift/codegen/src/regalloc/safepoint.rs
index 9b27b6227d..ba846190f3 100644
--- a/cranelift/codegen/src/regalloc/safepoint.rs
+++ b/cranelift/codegen/src/regalloc/safepoint.rs
@@ -4,7 +4,7 @@ use crate::ir::{Function, InstBuilder, InstructionData, Opcode, TrapCode};
 use crate::isa::TargetIsa;
 use crate::regalloc::live_value_tracker::LiveValueTracker;
 use crate::regalloc::liveness::Liveness;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 fn insert_and_encode_safepoint<'f>(
     pos: &mut FuncCursor<'f>,
diff --git a/cranelift/codegen/src/regalloc/solver.rs b/cranelift/codegen/src/regalloc/solver.rs
index 35e17b050d..8d651f143c 100644
--- a/cranelift/codegen/src/regalloc/solver.rs
+++ b/cranelift/codegen/src/regalloc/solver.rs
@@ -109,7 +109,7 @@ use core::fmt;
 use core::mem;
 use core::u16;
 use log::debug;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// A variable in the constraint problem.
 ///
@@ -1160,7 +1160,7 @@ mod tests {
     use crate::isa::{RegClass, RegInfo, RegUnit, TargetIsa};
     use crate::regalloc::RegisterSet;
     use core::str::FromStr;
-    use std::boxed::Box;
+    use alloc::boxed::Box;
     use target_lexicon::triple;
 
     // Make an arm32 `TargetIsa`, if possible.
diff --git a/cranelift/codegen/src/regalloc/spilling.rs b/cranelift/codegen/src/regalloc/spilling.rs
index ace368d798..3b42bcb5e5 100644
--- a/cranelift/codegen/src/regalloc/spilling.rs
+++ b/cranelift/codegen/src/regalloc/spilling.rs
@@ -29,7 +29,7 @@ use crate::timing;
 use crate::topo_order::TopoOrder;
 use core::fmt;
 use log::debug;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Return a top-level register class which contains `unit`.
 fn toprc_containing_regunit(unit: RegUnit, reginfo: &RegInfo) -> RegClass {
diff --git a/cranelift/codegen/src/regalloc/virtregs.rs b/cranelift/codegen/src/regalloc/virtregs.rs
index df2b480490..e3944b3cc2 100644
--- a/cranelift/codegen/src/regalloc/virtregs.rs
+++ b/cranelift/codegen/src/regalloc/virtregs.rs
@@ -22,7 +22,7 @@ use core::cmp::Ordering;
 use core::fmt;
 use core::slice;
 use smallvec::SmallVec;
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// A virtual register reference.
 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
diff --git a/cranelift/codegen/src/settings.rs b/cranelift/codegen/src/settings.rs
index c310972170..99e1562cc5 100644
--- a/cranelift/codegen/src/settings.rs
+++ b/cranelift/codegen/src/settings.rs
@@ -25,8 +25,8 @@ use crate::isa::TargetIsa;
 use core::fmt;
 use core::str;
 use failure_derive::Fail;
-use std::boxed::Box;
-use std::string::{String, ToString};
+use alloc::boxed::Box;
+use alloc::string::{String, ToString};
 
 /// A string-based configurator for settings groups.
 ///
@@ -369,7 +369,7 @@ mod tests {
     use super::Configurable;
     use super::SetError::*;
     use super::{builder, Flags};
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn display_default() {
diff --git a/cranelift/codegen/src/simple_gvn.rs b/cranelift/codegen/src/simple_gvn.rs
index 21a0b9beb9..f88f6f7a5c 100644
--- a/cranelift/codegen/src/simple_gvn.rs
+++ b/cranelift/codegen/src/simple_gvn.rs
@@ -7,7 +7,7 @@ use crate::scoped_hash_map::ScopedHashMap;
 use crate::timing;
 use core::cell::{Ref, RefCell};
 use core::hash::{Hash, Hasher};
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Test whether the given opcode is unsafe to even consider for GVN.
 fn trivially_unsafe_for_gvn(opcode: Opcode) -> bool {
diff --git a/cranelift/codegen/src/timing.rs b/cranelift/codegen/src/timing.rs
index 2a2d393803..34ba801593 100644
--- a/cranelift/codegen/src/timing.rs
+++ b/cranelift/codegen/src/timing.rs
@@ -252,7 +252,7 @@ mod details {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn display() {
diff --git a/cranelift/codegen/src/topo_order.rs b/cranelift/codegen/src/topo_order.rs
index 8824f4cc0a..647a8da941 100644
--- a/cranelift/codegen/src/topo_order.rs
+++ b/cranelift/codegen/src/topo_order.rs
@@ -3,7 +3,7 @@
 use crate::dominator_tree::DominatorTree;
 use crate::entity::EntitySet;
 use crate::ir::{Ebb, Layout};
-use std::vec::Vec;
+use alloc::vec::Vec;
 
 /// Present EBBs in a topological order such that all dominating EBBs are guaranteed to be visited
 /// before the current EBB.
diff --git a/cranelift/codegen/src/value_label.rs b/cranelift/codegen/src/value_label.rs
index 3d5802f12e..e11df7b9e8 100644
--- a/cranelift/codegen/src/value_label.rs
+++ b/cranelift/codegen/src/value_label.rs
@@ -6,8 +6,8 @@ use core::cmp::Ordering;
 use core::iter::Iterator;
 use core::ops::Bound::*;
 use core::ops::Deref;
-use std::collections::BTreeMap;
-use std::vec::Vec;
+use alloc::collections::BTreeMap;
+use alloc::vec::Vec;
 
 #[cfg(feature = "enable-serde")]
 use serde::{Deserialize, Serialize};
diff --git a/cranelift/codegen/src/verifier/mod.rs b/cranelift/codegen/src/verifier/mod.rs
index 02cc3f0c52..fe9f1b10de 100644
--- a/cranelift/codegen/src/verifier/mod.rs
+++ b/cranelift/codegen/src/verifier/mod.rs
@@ -75,9 +75,9 @@ use crate::timing;
 use core::cmp::Ordering;
 use core::fmt::{self, Display, Formatter, Write};
 use failure_derive::Fail;
-use std::collections::BTreeSet;
-use std::string::String;
-use std::vec::Vec;
+use alloc::collections::BTreeSet;
+use alloc::string::String;
+use alloc::vec::Vec;
 
 pub use self::cssa::verify_cssa;
 pub use self::liveness::verify_liveness;
diff --git a/cranelift/codegen/src/write.rs b/cranelift/codegen/src/write.rs
index 8f5f81d23e..bc4e4ca58c 100644
--- a/cranelift/codegen/src/write.rs
+++ b/cranelift/codegen/src/write.rs
@@ -15,8 +15,8 @@ use crate::packed_option::ReservedValue;
 use crate::value_label::ValueLabelsRanges;
 use crate::HashSet;
 use core::fmt::{self, Write};
-use std::string::String;
-use std::vec::Vec;
+use alloc::string::String;
+use alloc::vec::Vec;
 
 /// A `FuncWriter` used to decorate functions during printing.
 pub trait FuncWriter {
@@ -759,7 +759,7 @@ mod tests {
     use crate::cursor::{Cursor, CursorPosition, FuncCursor};
     use crate::ir::types;
     use crate::ir::{ExternalName, Function, InstBuilder, StackSlotData, StackSlotKind};
-    use std::string::ToString;
+    use alloc::string::ToString;
 
     #[test]
     fn basic() {