diff --git a/cranelift/codegen/Cargo.toml b/cranelift/codegen/Cargo.toml
index eb6a1094c8..e38f06d608 100644
--- a/cranelift/codegen/Cargo.toml
+++ b/cranelift/codegen/Cargo.toml
@@ -18,7 +18,7 @@ cranelift-entity = { path = "../cranelift-entity", version = "0.44.0", default-f
 cranelift-bforest = { path = "../cranelift-bforest", version = "0.44.0", default-features = false }
 failure = { version = "0.1.1", default-features = false, features = ["derive"] }
 failure_derive = { version = "0.1.1", default-features = false }
-hashmap_core = { version = "0.1.9", optional = true }
+hashbrown = { version = "0.6", optional = true }
 target-lexicon = "0.8.1"
 log = { version = "0.4.6", default-features = false }
 serde = { version = "1.0.94", features = ["derive"], optional = true }
@@ -43,10 +43,10 @@ std = [
     "cranelift-codegen-meta/std"
 ]
 
-# The "core" features enables use of "hashmap_core" since core doesn't have
+# The "core" features enables use of "hashbrown" since core doesn't have
 # a HashMap implementation, and a workaround for Cargo #4866.
 core = [
-    "hashmap_core",
+    "hashbrown",
     "cranelift-codegen-meta/core"
 ]
 
diff --git a/cranelift/codegen/src/binemit/memorysink.rs b/cranelift/codegen/src/binemit/memorysink.rs
index ffb8b44b49..ac3e82bea2 100644
--- a/cranelift/codegen/src/binemit/memorysink.rs
+++ b/cranelift/codegen/src/binemit/memorysink.rs
@@ -99,7 +99,7 @@ impl<'a> MemoryCodeSink<'a> {
         unsafe {
             #[cfg_attr(feature = "cargo-clippy", allow(clippy::cast_ptr_alignment))]
             write_unaligned(self.data.offset(self.offset) as *mut T, x);
-            self.offset += std::mem::size_of::<T>() as isize;
+            self.offset += core::mem::size_of::<T>() as isize;
         }
     }
 }
diff --git a/cranelift/codegen/src/binemit/stackmap.rs b/cranelift/codegen/src/binemit/stackmap.rs
index 4051b47e19..5d6844dcf3 100644
--- a/cranelift/codegen/src/binemit/stackmap.rs
+++ b/cranelift/codegen/src/binemit/stackmap.rs
@@ -4,7 +4,7 @@ use crate::isa::TargetIsa;
 use std::vec::Vec;
 
 type Num = u32;
-const NUM_BITS: usize = std::mem::size_of::<Num>() * 8;
+const NUM_BITS: usize = core::mem::size_of::<Num>() * 8;
 
 /// Wrapper class for longer bit vectors that cannot be represented by a single BitSet.
 #[derive(Clone, Debug)]
@@ -20,7 +20,7 @@ impl Stackmap {
         isa: &dyn TargetIsa,
     ) -> Self {
         let loc = &func.locations;
-        let mut live_ref_in_stack_slot = std::collections::HashSet::new();
+        let mut live_ref_in_stack_slot = crate::HashSet::new();
         // References can be in registers, and live registers values are pushed onto the stack before calls and traps.
         // TODO: Implement register maps. If a register containing a reference is spilled and reused after a safepoint,
         // it could contain a stale reference value if the garbage collector relocated the value.
diff --git a/cranelift/codegen/src/divconst_magic_numbers.rs b/cranelift/codegen/src/divconst_magic_numbers.rs
index b155496ab9..7b302e9b1a 100644
--- a/cranelift/codegen/src/divconst_magic_numbers.rs
+++ b/cranelift/codegen/src/divconst_magic_numbers.rs
@@ -1078,8 +1078,6 @@ mod tests {
                 d -= 1;
             }
         }
-
         assert_eq!(n_tests_done, 50_148_000);
     }
-
 }
diff --git a/cranelift/codegen/src/ir/constant.rs b/cranelift/codegen/src/ir/constant.rs
index c22380db55..9f21209c4c 100644
--- a/cranelift/codegen/src/ir/constant.rs
+++ b/cranelift/codegen/src/ir/constant.rs
@@ -9,8 +9,9 @@
 //! - bucketing constants by size.
 
 use crate::ir::Constant;
+use crate::HashMap;
 use cranelift_entity::EntityRef;
-use std::collections::{BTreeMap, HashMap};
+use std::collections::BTreeMap;
 use std::vec::Vec;
 
 /// This type describes the actual constant data.
diff --git a/cranelift/codegen/src/ir/dfg.rs b/cranelift/codegen/src/ir/dfg.rs
index 5b3054b59d..e4ec9c6be8 100644
--- a/cranelift/codegen/src/ir/dfg.rs
+++ b/cranelift/codegen/src/ir/dfg.rs
@@ -13,12 +13,12 @@ use crate::ir::{
 use crate::isa::TargetIsa;
 use crate::packed_option::ReservedValue;
 use crate::write::write_operands;
+use crate::HashMap;
 use core::fmt;
 use core::iter;
 use core::mem;
 use core::ops::{Index, IndexMut};
 use core::u16;
-use std::collections::HashMap;
 use std::vec::Vec;
 
 /// A data flow graph defines all instructions and extended basic blocks in a function as well as
diff --git a/cranelift/codegen/src/lib.rs b/cranelift/codegen/src/lib.rs
index 73f2114561..0e61171d14 100644
--- a/cranelift/codegen/src/lib.rs
+++ b/cranelift/codegen/src/lib.rs
@@ -50,7 +50,7 @@ extern crate alloc as std;
 extern crate std;
 
 #[cfg(not(feature = "std"))]
-use hashmap_core::{map as hash_map, HashMap, HashSet};
+use hashbrown::{hash_map, HashMap, HashSet};
 #[cfg(feature = "std")]
 use std::collections::{hash_map, HashMap, HashSet};
 
diff --git a/cranelift/codegen/src/scoped_hash_map.rs b/cranelift/codegen/src/scoped_hash_map.rs
index fe22e26ce3..809d22132a 100644
--- a/cranelift/codegen/src/scoped_hash_map.rs
+++ b/cranelift/codegen/src/scoped_hash_map.rs
@@ -8,6 +8,11 @@ use crate::fx::FxHashMap;
 use core::hash::Hash;
 use core::mem;
 
+#[cfg(not(feature = "std"))]
+use crate::fx::FxHasher;
+#[cfg(not(feature = "std"))]
+type Hasher = core::hash::BuildHasherDefault<FxHasher>;
+
 struct Val<K, V> {
     value: V,
     next_key: Option<K>,
@@ -16,7 +21,10 @@ struct Val<K, V> {
 
 /// A view into an occupied entry in a `ScopedHashMap`. It is part of the `Entry` enum.
 pub struct OccupiedEntry<'a, K: 'a, V: 'a> {
+    #[cfg(feature = "std")]
     entry: super::hash_map::OccupiedEntry<'a, K, Val<K, V>>,
+    #[cfg(not(feature = "std"))]
+    entry: super::hash_map::OccupiedEntry<'a, K, Val<K, V>, Hasher>,
 }
 
 impl<'a, K, V> OccupiedEntry<'a, K, V> {
@@ -28,12 +36,15 @@ impl<'a, K, V> OccupiedEntry<'a, K, V> {
 
 /// A view into a vacant entry in a `ScopedHashMap`. It is part of the `Entry` enum.
 pub struct VacantEntry<'a, K: 'a, V: 'a> {
+    #[cfg(feature = "std")]
     entry: super::hash_map::VacantEntry<'a, K, Val<K, V>>,
+    #[cfg(not(feature = "std"))]
+    entry: super::hash_map::VacantEntry<'a, K, Val<K, V>, Hasher>,
     next_key: Option<K>,
     depth: usize,
 }
 
-impl<'a, K, V> VacantEntry<'a, K, V> {
+impl<'a, K: Hash, V> VacantEntry<'a, K, V> {
     /// Sets the value of the entry with the `VacantEntry`'s key.
     pub fn insert(self, value: V) {
         self.entry.insert(Val {
diff --git a/cranelift/codegen/src/value_label.rs b/cranelift/codegen/src/value_label.rs
index d3d1e0672c..b6ad71faf8 100644
--- a/cranelift/codegen/src/value_label.rs
+++ b/cranelift/codegen/src/value_label.rs
@@ -1,11 +1,12 @@
 use crate::ir::{Function, SourceLoc, Value, ValueLabel, ValueLabelAssignments, ValueLoc};
 use crate::isa::TargetIsa;
 use crate::regalloc::{Context, RegDiversions};
-use std::cmp::Ordering;
-use std::collections::{BTreeMap, HashMap};
-use std::iter::Iterator;
-use std::ops::Bound::*;
-use std::ops::Deref;
+use crate::HashMap;
+use core::cmp::Ordering;
+use core::iter::Iterator;
+use core::ops::Bound::*;
+use core::ops::Deref;
+use std::collections::BTreeMap;
 use std::vec::Vec;
 
 #[cfg(feature = "enable-serde")]
diff --git a/cranelift/codegen/src/write.rs b/cranelift/codegen/src/write.rs
index 8d974c1ec5..8f5f81d23e 100644
--- a/cranelift/codegen/src/write.rs
+++ b/cranelift/codegen/src/write.rs
@@ -13,8 +13,8 @@ use crate::ir::{
 use crate::isa::{RegInfo, TargetIsa};
 use crate::packed_option::ReservedValue;
 use crate::value_label::ValueLabelsRanges;
+use crate::HashSet;
 use core::fmt::{self, Write};
-use std::collections::HashSet;
 use std::string::String;
 use std::vec::Vec;
 
diff --git a/cranelift/entity/src/map.rs b/cranelift/entity/src/map.rs
index 77fe38ce92..884f812fb2 100644
--- a/cranelift/entity/src/map.rs
+++ b/cranelift/entity/src/map.rs
@@ -3,6 +3,7 @@
 use crate::iter::{Iter, IterMut};
 use crate::keys::Keys;
 use crate::EntityRef;
+use core::cmp::min;
 use core::marker::PhantomData;
 use core::ops::{Index, IndexMut};
 use core::slice;
@@ -12,7 +13,6 @@ use serde::{
     ser::{SerializeSeq, Serializer},
     Deserialize, Serialize,
 };
-use std::cmp::min;
 use std::vec::Vec;
 
 /// A mapping `K -> V` for densely indexed entity references.
diff --git a/cranelift/frontend/Cargo.toml b/cranelift/frontend/Cargo.toml
index e30bde657e..0f8aefe91d 100644
--- a/cranelift/frontend/Cargo.toml
+++ b/cranelift/frontend/Cargo.toml
@@ -14,13 +14,13 @@ edition = "2018"
 cranelift-codegen = { path = "../cranelift-codegen", version = "0.44.0", default-features = false }
 target-lexicon = "0.8.1"
 log = { version = "0.4.6", default-features = false }
-hashmap_core = { version = "0.1.9", optional = true }
+hashbrown = { version = "0.6", optional = true }
 smallvec = { version = "0.6.10" }
 
 [features]
 default = ["std"]
 std = ["cranelift-codegen/std"]
-core = ["hashmap_core", "cranelift-codegen/core"]
+core = ["hashbrown", "cranelift-codegen/core"]
 
 # Temporary feature that enforces basic block semantics.
 basic-blocks = ["cranelift-codegen/basic-blocks"]
diff --git a/cranelift/frontend/src/frontend.rs b/cranelift/frontend/src/frontend.rs
index fbd2428e1c..6204071618 100644
--- a/cranelift/frontend/src/frontend.rs
+++ b/cranelift/frontend/src/frontend.rs
@@ -341,7 +341,7 @@ impl<'a> FunctionBuilder<'a> {
     /// This will not do anything unless `func.dfg.collect_debug_info` is called first.
     pub fn set_val_label(&mut self, val: Value, label: ValueLabel) {
         if let Some(values_labels) = self.func.dfg.values_labels.as_mut() {
-            use std::collections::hash_map::Entry;
+            use crate::hash_map::Entry;
 
             let start = ValueLabelStart {
                 from: self.srcloc,
diff --git a/cranelift/frontend/src/lib.rs b/cranelift/frontend/src/lib.rs
index eff5c655fd..5e53944901 100644
--- a/cranelift/frontend/src/lib.rs
+++ b/cranelift/frontend/src/lib.rs
@@ -191,9 +191,9 @@ extern crate alloc as std;
 extern crate std;
 
 #[cfg(not(feature = "std"))]
-use hashmap_core::HashMap;
+use hashbrown::{hash_map, HashMap};
 #[cfg(feature = "std")]
-use std::collections::HashMap;
+use std::collections::{hash_map, HashMap};
 
 pub use crate::frontend::{FunctionBuilder, FunctionBuilderContext};
 pub use crate::switch::Switch;
diff --git a/cranelift/module/Cargo.toml b/cranelift/module/Cargo.toml
index 890c1a5778..2ce44cc32c 100644
--- a/cranelift/module/Cargo.toml
+++ b/cranelift/module/Cargo.toml
@@ -13,14 +13,14 @@ edition = "2018"
 [dependencies]
 cranelift-codegen = { path = "../cranelift-codegen", version = "0.44.0", default-features = false }
 cranelift-entity = { path = "../cranelift-entity", version = "0.44.0", default-features = false }
-hashmap_core = { version = "0.1.9", optional = true }
+hashbrown = { version = "0.6", optional = true }
 failure = { version = "0.1.1", default-features = false }
 log = { version = "0.4.6", default-features = false }
 
 [features]
 default = ["std"]
 std = ["cranelift-codegen/std", "cranelift-entity/std"]
-core = ["hashmap_core", "cranelift-codegen/core"]
+core = ["hashbrown", "cranelift-codegen/core"]
 
 [badges]
 maintenance = { status = "experimental" }
diff --git a/cranelift/module/src/lib.rs b/cranelift/module/src/lib.rs
index 7cb9c10f22..0122171e9a 100644
--- a/cranelift/module/src/lib.rs
+++ b/cranelift/module/src/lib.rs
@@ -28,7 +28,7 @@ extern crate alloc as std;
 extern crate std;
 
 #[cfg(not(feature = "std"))]
-use hashmap_core::{map as hash_map, HashMap};
+use hashbrown::{hash_map, HashMap};
 #[cfg(feature = "std")]
 use std::collections::{hash_map, HashMap};
 
diff --git a/cranelift/wasm/Cargo.toml b/cranelift/wasm/Cargo.toml
index fd7f51608d..5e2a9e1cbe 100644
--- a/cranelift/wasm/Cargo.toml
+++ b/cranelift/wasm/Cargo.toml
@@ -15,7 +15,7 @@ wasmparser = { version = "0.39.1", default-features = false }
 cranelift-codegen = { path = "../cranelift-codegen", version = "0.44.0", default-features = false }
 cranelift-entity = { path = "../cranelift-entity", version = "0.44.0", default-features = false }
 cranelift-frontend = { path = "../cranelift-frontend", version = "0.44.0", default-features = false }
-hashmap_core = { version = "0.1.9", optional = true }
+hashbrown = { version = "0.6", optional = true }
 failure = { version = "0.1.1", default-features = false, features = ["derive"] }
 failure_derive = { version = "0.1.1", default-features = false }
 log = { version = "0.4.6", default-features = false }
@@ -28,7 +28,7 @@ target-lexicon = "0.8.1"
 [features]
 default = ["std"]
 std = ["cranelift-codegen/std", "cranelift-frontend/std", "wasmparser/std"]
-core = ["hashmap_core", "cranelift-codegen/core", "cranelift-frontend/core", "wasmparser/core"]
+core = ["hashbrown", "cranelift-codegen/core", "cranelift-frontend/core", "wasmparser/core"]
 enable-serde = ["serde"]
 
 # Temporary feature that enforces basic block semantics.
diff --git a/cranelift/wasm/src/lib.rs b/cranelift/wasm/src/lib.rs
index d47feb631d..297c9df5f0 100644
--- a/cranelift/wasm/src/lib.rs
+++ b/cranelift/wasm/src/lib.rs
@@ -37,9 +37,10 @@ extern crate alloc as std;
 extern crate std;
 
 #[cfg(not(feature = "std"))]
-use hashmap_core::{
+use hashbrown::{
+    hash_map,
     hash_map::Entry::{Occupied, Vacant},
-    map as hash_map, HashMap,
+    HashMap,
 };
 #[cfg(feature = "std")]
 use std::collections::{