--- a/browser/config/mozconfigs/linux64/plain-opt
+++ b/browser/config/mozconfigs/linux64/plain-opt
@@ -1,12 +1,13 @@
 export TOOLTOOL_DIR="$topsrcdir"
 export LLVM_CONFIG="${TOOLTOOL_DIR}/clang/bin/llvm-config"
 
 CARGO="${TOOLTOOL_DIR}/rustc/bin/cargo"
 RUSTC="${TOOLTOOL_DIR}/rustc/bin/rustc"
 RUSTDOC="${TOOLTOOL_DIR}/rustc/bin/rustdoc"
+RUSTFMT="${TOOLTOOL_DIR}/rustc/bin/rustfmt"
 
 CC="${TOOLTOOL_DIR}/gcc/bin/gcc"
 CXX="${TOOLTOOL_DIR}/gcc/bin/g++"
 
 mk_add_options "export PATH=${TOOLTOOL_DIR}/gcc/bin:${PATH}"
 mk_add_options "export LD_LIBRARY_PATH=${TOOLTOOL_DIR}/gcc/lib64:${TOOLTOOL_DIR}/gcc/lib32:${TOOLTOOL_DIR}/gcc/lib"

--- a/browser/config/mozconfigs/win64/plain-opt
+++ b/browser/config/mozconfigs/win64/plain-opt
@@ -1,12 +1,13 @@
 TOOLTOOL_DIR=${topsrcdir}
 export MAKECAB=$TOOLTOOL_DIR/makecab.exe
 export LLVM_CONFIG="${TOOLTOOL_DIR}/clang/bin/llvm-config"
 
 RUSTC="${TOOLTOOL_DIR}/rustc/bin/rustc"
 CARGO="${TOOLTOOL_DIR}/rustc/bin/cargo"
 RUSTDOC="${TOOLTOOL_DIR}/rustc/bin/rustdoc"
+RUSTFMT="${TOOLTOOL_DIR}/rustc/bin/rustfmt"
 
 ac_add_options --target=x86_64-pc-mingw32
 ac_add_options --host=x86_64-pc-mingw32
 
 . $topsrcdir/build/win64/mozconfig.vs-latest

--- a/build/moz.configure/rust.configure
+++ b/build/moz.configure/rust.configure
@@ -273,16 +273,19 @@ option('--enable-rust-tests',
 def rust_tests(enable_rust_tests, rustdoc):
     if enable_rust_tests and not rustdoc:
         die('--enable-rust-tests requires rustdoc')
     return bool(enable_rust_tests)
 
 
 set_config('MOZ_RUST_TESTS', rust_tests)
 
+# Bindgen can use rustfmt to format Rust file, but it's not required.
+rustfmt = check_prog('RUSTFMT', add_rustup_path('rustfmt'), allow_missing=True)
+
 option(env='WIN64_LINK', nargs=1, help='Path to link.exe that targets win64')
 option(env='WIN64_LIB', nargs=1, help='Paths to libraries for the win64 linker')
 
 set_config('WIN64_LINK', depends('WIN64_LINK')(lambda x: x))
 set_config('WIN64_LIB', depends('WIN64_LIB')(lambda x: x))
 
 
 @depends(target, rustc_info, c_compiler, 'WIN64_LINK', 'WIN64_LIB')

--- a/build/mozconfig.no-compile
+++ b/build/mozconfig.no-compile
@@ -10,16 +10,17 @@ NO_CACHE=1
 unset CC
 unset CXX
 unset HOST_CC
 unset HOST_CXX
 unset LINKER
 unset RUSTC
 unset CARGO
 unset RUSTDOC
+unset RUSTFMT
 unset MAKECAB
 unset TOOLCHAIN_PREFIX
 unset BINDGEN_CFLAGS
 unset LLVM_CONFIG
 unset WIN64_LINK
 unset WIN64_LIB
 
 unset MOZ_STDCXX_COMPAT

--- a/build/mozconfig.rust
+++ b/build/mozconfig.rust
@@ -1,10 +1,11 @@
 # Options to enable rust in automation builds.
 
 TOOLTOOL_DIR=${TOOLTOOL_DIR:-$topsrcdir}
 
 # Tell configure to use the tooltool rustc.
 RUSTC="$TOOLTOOL_DIR/rustc/bin/rustc"
 CARGO="$TOOLTOOL_DIR/rustc/bin/cargo"
 RUSTDOC="$TOOLTOOL_DIR/rustc/bin/rustdoc"
+RUSTFMT="$TOOLTOOL_DIR/rustc/bin/rustfmt"
 
 ac_add_options --enable-rust-simd

--- a/config/rules.mk
+++ b/config/rules.mk
@@ -877,16 +877,17 @@ endif
 # We use the + prefix to pass down the jobserver fds to cargo, but we
 # don't use the prefix when make -n is used, so that cargo doesn't run
 # in that case)
 define RUN_CARGO
 $(if $(findstring n,$(filter-out --%, $(MAKEFLAGS))),,+)env $(environment_cleaner) $(rust_unlock_unstable) $(rustflags_override) $(sccache_wrap) \
 	CARGO_TARGET_DIR=$(CARGO_TARGET_DIR) \
 	RUSTC=$(RUSTC) \
 	RUSTDOC=$(RUSTDOC) \
+	RUSTFMT=$(RUSTFMT) \
 	MOZ_SRC=$(topsrcdir) \
 	MOZ_DIST=$(ABS_DIST) \
 	LIBCLANG_PATH="$(MOZ_LIBCLANG_PATH)" \
 	CLANG_PATH="$(MOZ_CLANG_PATH)" \
 	PKG_CONFIG_ALLOW_CROSS=1 \
 	RUST_BACKTRACE=full \
 	MOZ_TOPOBJDIR=$(topobjdir) \
 	$(cargo_incremental) \