diff --git a/js/rust/Cargo.toml b/js/rust/Cargo.toml
index 624dfc6cd040..d821f24f7ce7 100644
--- a/js/rust/Cargo.toml
+++ b/js/rust/Cargo.toml
@@ -39,6 +39,7 @@ doctest = false
 debugmozjs = ['mozjs_sys/debugmozjs']
 promises = ['mozjs_sys/promises']
 nonzero = []
+bigint = ['mozjs_sys/bigint']
 
 [dependencies.mozjs_sys]
 path = "../src"
diff --git a/js/rust/build.rs b/js/rust/build.rs
index 38475a73783d..e85d3b730acc 100644
--- a/js/rust/build.rs
+++ b/js/rust/build.rs
@@ -73,6 +73,10 @@ fn build_jsapi_bindings() {
             .clang_arg("-DJS_DEBUG");
     }
 
+    if cfg!(feature = "bigint") {
+        builder = builder.clang_arg("-DENABLE_BIGINT");
+    }
+
     let include_dir = get_mozjs_include_dir();
     let include_dir = include_dir.to_str()
         .expect("Path to mozjs include dir should be utf-8");
@@ -99,6 +103,10 @@ fn build_jsapi_bindings() {
         builder = builder.whitelist_function(func);
     }
 
+    if cfg!(feature = "bigint") {
+        builder = builder.whitelist_type("JS::BigInt");
+    }
+
     for ty in OPAQUE_TYPES {
         builder = builder.opaque_type(ty);
     }
diff --git a/js/rust/src/jsval.rs b/js/rust/src/jsval.rs
index 6df051e0754a..ac9e42647494 100644
--- a/js/rust/src/jsval.rs
+++ b/js/rust/src/jsval.rs
@@ -25,6 +25,8 @@ enum ValueTag {
     UNDEFINED = JSVAL_TAG_MAX_DOUBLE | (JSValueType::JSVAL_TYPE_UNDEFINED as u32),
     STRING    = JSVAL_TAG_MAX_DOUBLE | (JSValueType::JSVAL_TYPE_STRING as u32),
     SYMBOL    = JSVAL_TAG_MAX_DOUBLE | (JSValueType::JSVAL_TYPE_SYMBOL as u32),
+    #[cfg(feature = "bigint")]
+    BIGINT    = JSVAL_TAG_MAX_DOUBLE | (JSValueType::JSVAL_TYPE_BIGINT as u32),
     BOOLEAN   = JSVAL_TAG_MAX_DOUBLE | (JSValueType::JSVAL_TYPE_BOOLEAN as u32),
     MAGIC     = JSVAL_TAG_MAX_DOUBLE | (JSValueType::JSVAL_TYPE_MAGIC as u32),
     NULL      = JSVAL_TAG_MAX_DOUBLE | (JSValueType::JSVAL_TYPE_NULL as u32),
@@ -41,6 +43,8 @@ enum ValueTag {
     UNDEFINED = JSVAL_TAG_CLEAR as u32 | (JSValueType::JSVAL_TYPE_UNDEFINED as u32),
     STRING    = JSVAL_TAG_CLEAR as u32 | (JSValueType::JSVAL_TYPE_STRING as u32),
     SYMBOL    = JSVAL_TAG_CLEAR as u32 | (JSValueType::JSVAL_TYPE_SYMBOL as u32),
+    #[cfg(feature = "bigint")]
+    BIGINT    = JSVAL_TAG_CLEAR as u32 | (JSValueType::JSVAL_TYPE_BIGINT as u32),
     BOOLEAN   = JSVAL_TAG_CLEAR as u32 | (JSValueType::JSVAL_TYPE_BOOLEAN as u32),
     MAGIC     = JSVAL_TAG_CLEAR as u32 | (JSValueType::JSVAL_TYPE_MAGIC as u32),
     NULL      = JSVAL_TAG_CLEAR as u32 | (JSValueType::JSVAL_TYPE_NULL as u32),
@@ -57,6 +61,8 @@ enum ValueShiftedTag {
     UNDEFINED  = ((ValueTag::UNDEFINED as u64)  << JSVAL_TAG_SHIFT),
     STRING     = ((ValueTag::STRING as u64)     << JSVAL_TAG_SHIFT),
     SYMBOL     = ((ValueTag::SYMBOL as u64)     << JSVAL_TAG_SHIFT),
+    #[cfg(feature = "bigint")]
+    BIGINT     = ((ValueTag::BIGINT as u64)     << JSVAL_TAG_SHIFT),
     BOOLEAN    = ((ValueTag::BOOLEAN as u64)    << JSVAL_TAG_SHIFT),
     MAGIC      = ((ValueTag::MAGIC as u64)      << JSVAL_TAG_SHIFT),
     NULL       = ((ValueTag::NULL as u64)       << JSVAL_TAG_SHIFT),
@@ -187,6 +193,23 @@ pub fn PrivateValue(o: *const c_void) -> JS::Value {
     BuildJSVal(ValueTag::PRIVATE, ptrBits)
 }
 
+#[inline(always)]
+#[cfg(feature = "bigint")]
+#[cfg(target_pointer_width = "64")]
+pub fn BigIntValue(b: &JS::BigInt) -> JS::Value {
+    let bits = b as *const JS::BigInt as usize as u64;
+    assert!((bits >> JSVAL_TAG_SHIFT) == 0);
+    BuildJSVal(ValueTag::BIGINT, bits)
+}
+
+#[inline(always)]
+#[cfg(target_pointer_width = "32")]
+#[inline(always)]
+pub fn BigIntValue(s: &JS::BigInt) -> JS::Value {
+    let bits = s as *const JS::BigInt as usize as u64;
+    BuildJSVal(ValueTag::BIGINT, bits)
+}
+
 impl JS::Value {
     #[inline(always)]
     unsafe fn asBits(&self) -> u64 {
@@ -363,6 +386,24 @@ impl JS::Value {
         }
     }
 
+    #[inline(always)]
+    #[cfg(feature = "bigint")]
+    #[cfg(target_pointer_width = "64")]
+    pub fn is_bigint(&self) -> bool {
+        unsafe {
+            (self.asBits() >> JSVAL_TAG_SHIFT) == ValueTag::BIGINT as u64
+        }
+    }
+
+    #[inline(always)]
+    #[cfg(feature = "bigint")]
+    #[cfg(target_pointer_width = "32")]
+    pub fn is_bigint(&self) -> bool {
+        unsafe {
+            (self.asBits() >> 32) == ValueTag::BIGINT as u64
+        }
+    }
+
     #[inline(always)]
     #[cfg(target_pointer_width = "64")]
     pub fn to_boolean(&self) -> bool {
diff --git a/js/rust/src/rust.rs b/js/rust/src/rust.rs
index 758d8ab4123c..71ce57c6bc99 100644
--- a/js/rust/src/rust.rs
+++ b/js/rust/src/rust.rs
@@ -306,6 +306,12 @@ impl RootKind for *mut JS::Symbol {
     fn rootKind() -> JS::RootKind { JS::RootKind::Symbol }
 }
 
+#[cfg(feature = "bigint")]
+impl RootKind for *mut JS::BigInt {
+    #[inline(always)]
+    fn rootKind() -> JS::RootKind { JS::RootKind::BigInt }
+}
+
 impl RootKind for *mut JSScript {
     #[inline(always)]
     fn rootKind() -> JS::RootKind { JS::RootKind::Script }
diff --git a/js/src/Cargo.toml b/js/src/Cargo.toml
index 4829b49b101e..060ea42f4b5d 100644
--- a/js/src/Cargo.toml
+++ b/js/src/Cargo.toml
@@ -8,6 +8,7 @@ build = "build.rs"
 [features]
 debugmozjs = []
 promises = []
+bigint = []
 
 [lib]
 name = "mozjs_sys"
diff --git a/js/src/build.rs b/js/src/build.rs
index 5230e5ed803c..e42c1020d0b8 100644
--- a/js/src/build.rs
+++ b/js/src/build.rs
@@ -16,11 +16,9 @@ fn main() {
     env::set_var("MAKEFLAGS", format!("-j{}", num_cpus::get()));
     env::set_current_dir(&js_src).unwrap();
 
-    let variant = if cfg!(feature = "debugmozjs") {
-        "plaindebug"
-    } else {
-        "plain"
-    };
+    let variant = format!("{}{}",
+                          if cfg!(feature = "bigint") { "bigint" } else { "plain" },
+                          if cfg!(feature = "debugmozjs") { "debug" } else { "" });
 
     let python = env::var("PYTHON").unwrap_or("python2.7".into());
     let mut cmd = Command::new(&python);
@@ -36,7 +34,7 @@ fn main() {
                // already exists but wasn't created by autospider.
                "--dep",
                "--objdir", &out_dir,
-               variant])
+               &variant])
         .env("SOURCE", &js_src)
         .env("PWD", &js_src)
         .stdout(Stdio::inherit())
@@ -54,6 +52,10 @@ fn main() {
     println!("cargo:rustc-link-search=native={}/dist/bin", out_dir);
     println!("cargo:rustc-link-lib=nspr4");
 
+    if cfg!(feature = "bigint") {
+        println!("cargo:rustc-link-lib=gmp");
+    }
+
     if target.contains("windows") {
         println!("cargo:rustc-link-lib=winmm");
         if target.contains("gnu") {
diff --git a/js/src/devtools/automation/variants/bigint b/js/src/devtools/automation/variants/bigint
new file mode 100644
index 000000000000..46cfd9d4c1c5
--- /dev/null
+++ b/js/src/devtools/automation/variants/bigint
@@ -0,0 +1,7 @@
+{
+    "configure-args": "--enable-bigint",
+    "optimize": true,
+    "env": {
+        "JSTESTS_EXTRA_ARGS": "--jitflags=all"
+    }
+}
diff --git a/js/src/devtools/automation/variants/bigintdebug b/js/src/devtools/automation/variants/bigintdebug
new file mode 100644
index 000000000000..c5f622fe84c3
--- /dev/null
+++ b/js/src/devtools/automation/variants/bigintdebug
@@ -0,0 +1,7 @@
+{
+    "configure-args": "--enable-bigint",
+    "debug": true,
+    "env": {
+        "JSTESTS_EXTRA_ARGS": "--jitflags=debug"
+    }
+}