diff --git a/substrate/Cargo.lock b/substrate/Cargo.lock
index c724f4c016..16d7939a70 100644
--- a/substrate/Cargo.lock
+++ b/substrate/Cargo.lock
@@ -2326,7 +2326,7 @@ dependencies = [
  "substrate-keyring 2.0.0",
  "substrate-offchain-primitives 2.0.0",
  "substrate-primitives 2.0.0",
- "substrate-wasm-builder-runner 1.0.1",
+ "substrate-wasm-builder-runner 1.0.2",
 ]
 
 [[package]]
@@ -2380,7 +2380,7 @@ dependencies = [
  "substrate-consensus-aura-primitives 2.0.0",
  "substrate-offchain-primitives 2.0.0",
  "substrate-primitives 2.0.0",
- "substrate-wasm-builder-runner 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "substrate-wasm-builder-runner 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -4609,7 +4609,7 @@ dependencies = [
  "sr-sandbox 2.0.0",
  "sr-std 2.0.0",
  "substrate-primitives 2.0.0",
- "substrate-wasm-builder-runner 1.0.1",
+ "substrate-wasm-builder-runner 1.0.2",
 ]
 
 [[package]]
@@ -4765,7 +4765,7 @@ dependencies = [
  "substrate-primitives 2.0.0",
  "substrate-test-runtime-client 2.0.0",
  "substrate-trie 2.0.0",
- "substrate-wasm-builder-runner 1.0.1",
+ "substrate-wasm-builder-runner 1.0.2",
  "trie-db 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -4845,11 +4845,11 @@ dependencies = [
 
 [[package]]
 name = "substrate-wasm-builder-runner"
-version = "1.0.1"
+version = "1.0.2"
 
 [[package]]
 name = "substrate-wasm-builder-runner"
-version = "1.0.1"
+version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -6171,7 +6171,7 @@ dependencies = [
 "checksum strum 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1810e25f576e7ffce1ff5243b37066da5ded0310b3274c20baaeccb1145b2806"
 "checksum strum_macros 0.14.0 (registry+https://github.com/rust-lang/crates.io-index)" = "572a2f4e53dd4c3483fd79e5cc10ddd773a3acb1169bbfe8762365e107110579"
 "checksum substrate-bip39 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "d69ace596e9ca97837cc41f8edcfc4e0a997f227d5fc153d1010b60a0fe9acda"
-"checksum substrate-wasm-builder-runner 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "131fa5f29b2a2e459f226411e4718ecda62e360123b7cfd76ae6a7da5bcaeb0d"
+"checksum substrate-wasm-builder-runner 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f52ecbff6cc3d6e5c6401828e15937b680f459d6803ce238f01fe615bc40d071"
 "checksum subtle 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2d67a5a62ba6e01cb2192ff309324cb4875d0c451d55fe2319433abe7a05a8ee"
 "checksum subtle 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "01dca13cf6c3b179864ab3292bd794e757618d35a7766b7c46050c614ba00829"
 "checksum syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)" = "b4d960b829a55e56db167e861ddb43602c003c7be0bee1d345021703fac2fb7c"
diff --git a/substrate/core/executor/runtime-test/Cargo.toml b/substrate/core/executor/runtime-test/Cargo.toml
index 4ad3446a91..26bf2f71bd 100644
--- a/substrate/core/executor/runtime-test/Cargo.toml
+++ b/substrate/core/executor/runtime-test/Cargo.toml
@@ -12,7 +12,7 @@ sandbox = { package = "sr-sandbox", path = "../../sr-sandbox", default-features
 substrate-primitives = { path = "../../primitives", default-features = false }
 
 [build-dependencies]
-wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.1", path = "../../utils/wasm-builder-runner" }
+wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.2", path = "../../utils/wasm-builder-runner" }
 
 [features]
 default = [ "std" ]
diff --git a/substrate/core/executor/runtime-test/build.rs b/substrate/core/executor/runtime-test/build.rs
index 7eaa5e53c3..a8a5e1cba5 100644
--- a/substrate/core/executor/runtime-test/build.rs
+++ b/substrate/core/executor/runtime-test/build.rs
@@ -21,7 +21,7 @@ fn main() {
 		"wasm_binary.rs",
 		WasmBuilderSource::CratesOrPath {
 			path: "../../utils/wasm-builder",
-			version: "1.0.3",
+			version: "1.0.4",
 		},
 	);
 }
diff --git a/substrate/core/test-runtime/Cargo.toml b/substrate/core/test-runtime/Cargo.toml
index 8e9fc85a8a..d14d324006 100644
--- a/substrate/core/test-runtime/Cargo.toml
+++ b/substrate/core/test-runtime/Cargo.toml
@@ -31,7 +31,7 @@ substrate-executor = { path = "../executor" }
 substrate-test-runtime-client = { path = "./client" }
 
 [build-dependencies]
-wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.1", path = "../utils/wasm-builder-runner" }
+wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.2", path = "../utils/wasm-builder-runner" }
 
 [features]
 default = [
diff --git a/substrate/core/test-runtime/build.rs b/substrate/core/test-runtime/build.rs
index 1870f11f80..f543f68ccd 100644
--- a/substrate/core/test-runtime/build.rs
+++ b/substrate/core/test-runtime/build.rs
@@ -21,7 +21,7 @@ fn main() {
 		"wasm_binary.rs",
 		WasmBuilderSource::CratesOrPath {
 			path: "../utils/wasm-builder",
-			version: "1.0.3",
+			version: "1.0.4",
 		},
 	);
 }
diff --git a/substrate/core/utils/wasm-builder-runner/Cargo.toml b/substrate/core/utils/wasm-builder-runner/Cargo.toml
index da21baf1d9..4046b7e4e2 100644
--- a/substrate/core/utils/wasm-builder-runner/Cargo.toml
+++ b/substrate/core/utils/wasm-builder-runner/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "substrate-wasm-builder-runner"
-version = "1.0.1"
+version = "1.0.2"
 authors = ["Parity Technologies <admin@parity.io>"]
 description = "Runner for substrate-wasm-builder"
 edition = "2018"
diff --git a/substrate/core/utils/wasm-builder-runner/src/lib.rs b/substrate/core/utils/wasm-builder-runner/src/lib.rs
index 4d77bde4d6..1558dbf220 100644
--- a/substrate/core/utils/wasm-builder-runner/src/lib.rs
+++ b/substrate/core/utils/wasm-builder-runner/src/lib.rs
@@ -30,6 +30,9 @@ use std::{env, process::{Command, self}, fs, path::{PathBuf, Path}};
 /// Environment variable that tells us to skip building the WASM binary.
 const SKIP_BUILD_ENV: &str = "SKIP_WASM_BUILD";
 
+/// Environment variable to extend the `RUSTFLAGS` variable given to the WASM build.
+const WASM_BUILD_RUSTFLAGS_ENV: &str = "WASM_BUILD_RUSTFLAGS";
+
 /// Environment variable that tells us to create a dummy WASM binary.
 ///
 /// This is useful for `cargo check` to speed-up the compilation.
@@ -93,6 +96,20 @@ impl WasmBuilderSource {
 	}
 }
 
+/// Build the currently built project as WASM binary and extend `RUSTFLAGS` with the given rustflags.
+///
+/// For more information, see [`build_current_project`].
+pub fn build_current_project_with_rustflags(
+	file_name: &str,
+	wasm_builder_source: WasmBuilderSource,
+	rustflags: &str,
+) {
+	let given_rustflags = env::var(WASM_BUILD_RUSTFLAGS_ENV).unwrap_or_default();
+	env::set_var(WASM_BUILD_RUSTFLAGS_ENV, format!("{} {}", given_rustflags, rustflags));
+
+	build_current_project(file_name, wasm_builder_source)
+}
+
 /// Build the currently built project as WASM binary.
 ///
 /// The current project is determined using the `CARGO_MANIFEST_DIR` environment variable.
diff --git a/substrate/core/utils/wasm-builder/README.md b/substrate/core/utils/wasm-builder/README.md
index 90d7494eb1..8a8c67d6a8 100644
--- a/substrate/core/utils/wasm-builder/README.md
+++ b/substrate/core/utils/wasm-builder/README.md
@@ -49,6 +49,7 @@ By using environment variables, you can configure which WASM binaries are built
 - `TRIGGER_WASM_BUILD` - Can be set to trigger a WASM build. On subsequent calls the value of the variable
                          needs to change. As WASM builder instructs `cargo` to watch for file changes
                          this environment variable should only be required in certain circumstances.
+- `WASM_BUILD_RUSTFLAGS` - Extend `RUSTFLAGS` given to `cargo build` while building the WASM binary.
 
 Each project can be skipped individually by using the environment variable `SKIP_PROJECT_NAME_WASM_BUILD`.
 Where `PROJECT_NAME` needs to be replaced by the name of the cargo project, e.g. `node-runtime` will
diff --git a/substrate/core/utils/wasm-builder/src/lib.rs b/substrate/core/utils/wasm-builder/src/lib.rs
index ef999f1008..779fa8db09 100644
--- a/substrate/core/utils/wasm-builder/src/lib.rs
+++ b/substrate/core/utils/wasm-builder/src/lib.rs
@@ -65,6 +65,7 @@
 //! - `TRIGGER_WASM_BUILD` - Can be set to trigger a WASM build. On subsequent calls the value of the variable
 //!                          needs to change. As WASM builder instructs `cargo` to watch for file changes
 //!                          this environment variable should only be required in certain circumstances.
+//! - `WASM_BUILD_RUSTFLAGS` - Extend `RUSTFLAGS` given to `cargo build` while building the WASM binary.
 //!
 //! Each project can be skipped individually by using the environment variable `SKIP_PROJECT_NAME_WASM_BUILD`.
 //! Where `PROJECT_NAME` needs to be replaced by the name of the cargo project, e.g. `node-runtime` will
@@ -92,6 +93,9 @@ const SKIP_BUILD_ENV: &str = "SKIP_WASM_BUILD";
 /// By default the WASM binary uses the same build type as the main cargo build.
 const WASM_BUILD_TYPE_ENV: &str = "WASM_BUILD_TYPE";
 
+/// Environment variable to extend the `RUSTFLAGS` variable given to the WASM build.
+const WASM_BUILD_RUSTFLAGS_ENV: &str = "WASM_BUILD_RUSTFLAGS";
+
 /// Build the currently built project as WASM binary.
 ///
 /// The current project is determined by using the `CARGO_MANIFEST_DIR` environment variable.
diff --git a/substrate/core/utils/wasm-builder/src/wasm_project.rs b/substrate/core/utils/wasm-builder/src/wasm_project.rs
index 2b05774054..0d348a5cf4 100644
--- a/substrate/core/utils/wasm-builder/src/wasm_project.rs
+++ b/substrate/core/utils/wasm-builder/src/wasm_project.rs
@@ -227,12 +227,7 @@ fn create_project(cargo_manifest: &Path, wasm_workspace: &Path) -> PathBuf {
 
 	fs::write(
 		project_folder.join("src/lib.rs"),
-		format!(
-			r#"
-				#![no_std]
-				pub use wasm_project::*;
-			"#
-		)
+		"#![no_std] pub use wasm_project::*;",
 	).expect("Project `lib.rs` writing can not fail; qed");
 
 	if let Some(crate_lock_file) = find_cargo_lock(cargo_manifest) {
@@ -265,9 +260,15 @@ fn is_release_build() -> bool {
 fn build_project(project: &Path) {
 	let manifest_path = project.join("Cargo.toml");
 	let mut build_cmd = crate::get_nightly_cargo();
+
+	let rustflags = format!(
+		"-C link-arg=--export-table {}",
+		env::var(crate::WASM_BUILD_RUSTFLAGS_ENV).unwrap_or_default(),
+	);
+
 	build_cmd.args(&["build", "--target=wasm32-unknown-unknown"])
 		.arg(format!("--manifest-path={}", manifest_path.display()))
-		.env("RUSTFLAGS", "-C link-arg=--export-table")
+		.env("RUSTFLAGS", rustflags)
 		// We don't want to call ourselves recursively
 		.env(crate::SKIP_BUILD_ENV, "");
 
@@ -347,4 +348,5 @@ fn generate_rerun_if_changed_instructions(
 	// Register our env variables
 	println!("cargo:rerun-if-env-changed={}", crate::SKIP_BUILD_ENV);
 	println!("cargo:rerun-if-env-changed={}", crate::WASM_BUILD_TYPE_ENV);
+	println!("cargo:rerun-if-env-changed={}", crate::WASM_BUILD_RUSTFLAGS_ENV);
 }
diff --git a/substrate/node-template/runtime/Cargo.toml b/substrate/node-template/runtime/Cargo.toml
index 9102ec5eb2..375a0ad64e 100644
--- a/substrate/node-template/runtime/Cargo.toml
+++ b/substrate/node-template/runtime/Cargo.toml
@@ -26,7 +26,7 @@ consensus-aura = { package = "substrate-consensus-aura-primitives", path = "../.
 offchain-primitives = { package = "substrate-offchain-primitives", path = "../../core/offchain/primitives", default-features = false }
 
 [build-dependencies]
-wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.1" }
+wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.2" }
 
 [features]
 default = ["std"]
diff --git a/substrate/node-template/runtime/build.rs b/substrate/node-template/runtime/build.rs
index 73490a6fd3..ccf58b138f 100644
--- a/substrate/node-template/runtime/build.rs
+++ b/substrate/node-template/runtime/build.rs
@@ -17,5 +17,5 @@
 use wasm_builder_runner::{build_current_project, WasmBuilderSource};
 
 fn main() {
-	build_current_project("wasm_binary.rs", WasmBuilderSource::Crates("1.0.3"));
+	build_current_project("wasm_binary.rs", WasmBuilderSource::Crates("1.0.4"));
 }
diff --git a/substrate/node/runtime/Cargo.toml b/substrate/node/runtime/Cargo.toml
index 9796455957..83708be6da 100644
--- a/substrate/node/runtime/Cargo.toml
+++ b/substrate/node/runtime/Cargo.toml
@@ -39,7 +39,7 @@ serde = { version = "1.0", optional = true }
 substrate-keyring = { path = "../../core/keyring", optional = true }
 
 [build-dependencies]
-wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.1", path = "../../core/utils/wasm-builder-runner" }
+wasm-builder-runner = { package = "substrate-wasm-builder-runner", version = "1.0.2", path = "../../core/utils/wasm-builder-runner" }
 
 [features]
 default = ["std"]
diff --git a/substrate/node/runtime/build.rs b/substrate/node/runtime/build.rs
index 5252068e56..39aecacb20 100644
--- a/substrate/node/runtime/build.rs
+++ b/substrate/node/runtime/build.rs
@@ -21,7 +21,7 @@ fn main() {
 		"wasm_binary.rs",
 		WasmBuilderSource::CratesOrPath {
 			path: "../../core/utils/wasm-builder",
-			version: "1.0.3",
+			version: "1.0.4",
 		},
 	);
 }