diff --git a/cranelift/codegen/Cargo.toml b/cranelift/codegen/Cargo.toml
index 5cde9d47df..e088e6f84a 100644
--- a/cranelift/codegen/Cargo.toml
+++ b/cranelift/codegen/Cargo.toml
@@ -20,6 +20,7 @@ failure_derive = { version = "0.1.1", default-features = false }
 hashmap_core = { version = "0.1.9", optional = true }
 target-lexicon = { version = "0.4.0", default-features = false }
 log = { version = "0.4.6", default-features = false }
+serde = { version = "1.0.94", features = ["derive"], optional = true }
 # It is a goal of the cranelift-codegen crate to have minimal external dependencies.
 # Please don't add any unless they are essential to the task of creating binary
 # machine code. Integration tests that need external dependencies can be
@@ -58,6 +59,9 @@ arm32 = []
 arm64 = []
 riscv = []
 
+# For dependent crates that want to serialize some parts of cranelift
+enable-serde = ["serde"]
+
 [badges]
 maintenance = { status = "experimental" }
 travis-ci = { repository = "CraneStation/cranelift" }
diff --git a/cranelift/codegen/src/binemit/mod.rs b/cranelift/codegen/src/binemit/mod.rs
index 21b07587ed..b0408e97e7 100644
--- a/cranelift/codegen/src/binemit/mod.rs
+++ b/cranelift/codegen/src/binemit/mod.rs
@@ -14,6 +14,8 @@ pub use crate::regalloc::RegDiversions;
 
 use crate::ir::{ExternalName, Function, Inst, JumpTable, SourceLoc, TrapCode};
 use core::fmt;
+#[cfg(feature = "enable-serde")]
+use serde::{Deserialize, Serialize};
 
 /// Offset in bytes from the beginning of the function.
 ///
@@ -26,6 +28,7 @@ pub type Addend = i64;
 
 /// Relocation kinds for every ISA
 #[derive(Copy, Clone, Debug)]
+#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
 pub enum Reloc {
     /// absolute 4-byte
     Abs4,
diff --git a/cranelift/codegen/src/ir/entities.rs b/cranelift/codegen/src/ir/entities.rs
index 2c05fbc84b..a2a405bc46 100644
--- a/cranelift/codegen/src/ir/entities.rs
+++ b/cranelift/codegen/src/ir/entities.rs
@@ -22,6 +22,8 @@
 use crate::entity::entity_impl;
 use core::fmt;
 use core::u32;
+#[cfg(feature = "enable-serde")]
+use serde::{Deserialize, Serialize};
 
 /// An opaque reference to an extended basic block in a function.
 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
@@ -103,6 +105,7 @@ impl GlobalValue {
 
 /// An opaque reference to a jump table.
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
 pub struct JumpTable(u32);
 entity_impl!(JumpTable, "jt");
 
diff --git a/cranelift/codegen/src/ir/libcall.rs b/cranelift/codegen/src/ir/libcall.rs
index 275e22a91f..f544dd5732 100644
--- a/cranelift/codegen/src/ir/libcall.rs
+++ b/cranelift/codegen/src/ir/libcall.rs
@@ -7,6 +7,8 @@ use crate::ir::{
 use crate::isa::{CallConv, RegUnit, TargetIsa};
 use core::fmt;
 use core::str::FromStr;
+#[cfg(feature = "enable-serde")]
+use serde::{Deserialize, Serialize};
 
 /// The name of a runtime library routine.
 ///
@@ -17,6 +19,7 @@ use core::str::FromStr;
 ///
 /// This list is likely to grow over time.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
 pub enum LibCall {
     /// probe for stack overflow. These are emitted for functions which need
     /// when the `probestack_enabled` setting is true.
diff --git a/cranelift/codegen/src/ir/sourceloc.rs b/cranelift/codegen/src/ir/sourceloc.rs
index ab5722a57d..a0d051d3aa 100644
--- a/cranelift/codegen/src/ir/sourceloc.rs
+++ b/cranelift/codegen/src/ir/sourceloc.rs
@@ -4,6 +4,8 @@
 //! location when instructions are transformed.
 
 use core::fmt;
+#[cfg(feature = "enable-serde")]
+use serde::{Deserialize, Serialize};
 
 /// A source location.
 ///
@@ -13,6 +15,7 @@ use core::fmt;
 /// The default source location uses the all-ones bit pattern `!0`. It is used for instructions
 /// that can't be given a real source location.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
 pub struct SourceLoc(u32);
 
 impl SourceLoc {
diff --git a/cranelift/entity/src/map.rs b/cranelift/entity/src/map.rs
index 9410cc2f90..a0d31a4309 100644
--- a/cranelift/entity/src/map.rs
+++ b/cranelift/entity/src/map.rs
@@ -56,11 +56,23 @@ where
         }
     }
 
+    /// Returns the number of elements in the underlying vector.
+    ///
+    /// The number is not necessarily the same as the length of the corresponding PrimaryMap.
+    pub fn len(&self) -> usize {
+        self.elems.len()
+    }
+
     /// Get the element at `k` if it exists.
     pub fn get(&self, k: K) -> Option<&V> {
         self.elems.get(k.index())
     }
 
+    /// Get the default value.
+    pub fn get_default(&self) -> &V {
+        &self.default
+    }
+
     /// Is this map completely empty?
     pub fn is_empty(&self) -> bool {
         self.elems.is_empty()
diff --git a/cranelift/wasm/Cargo.toml b/cranelift/wasm/Cargo.toml
index 53a64e7896..5f9bfc4737 100644
--- a/cranelift/wasm/Cargo.toml
+++ b/cranelift/wasm/Cargo.toml
@@ -19,6 +19,7 @@ hashmap_core = { version = "0.1.9", 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 }
+serde = { version = "1.0.94", features = ["derive"], optional = true }
 
 [dev-dependencies]
 wabt = "0.7.0"
@@ -28,6 +29,7 @@ target-lexicon = "0.4.0"
 default = ["std"]
 std = ["cranelift-codegen/std", "cranelift-frontend/std", "wasmparser/std"]
 core = ["hashmap_core", "cranelift-codegen/core", "cranelift-frontend/core", "wasmparser/core"]
+enable-serde = ["serde"]
 
 [badges]
 maintenance = { status = "experimental" }
diff --git a/cranelift/wasm/src/translation_utils.rs b/cranelift/wasm/src/translation_utils.rs
index c221f751ff..759e4ab4ff 100644
--- a/cranelift/wasm/src/translation_utils.rs
+++ b/cranelift/wasm/src/translation_utils.rs
@@ -3,10 +3,13 @@ use crate::environ::{WasmError, WasmResult};
 use core::u32;
 use cranelift_codegen::entity::entity_impl;
 use cranelift_codegen::ir;
+#[cfg(feature = "enable-serde")]
+use serde::{Deserialize, Serialize};
 use wasmparser;
 
 /// Index type of a function (imported or defined) inside the WebAssembly module.
 #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, Debug)]
+#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
 pub struct FuncIndex(u32);
 entity_impl!(FuncIndex);