diff --git a/compiler-rt/lib/builtins/riscv/mulsi3.S b/compiler-rt/lib/builtins/riscv/int_mul_impl.inc
copy from compiler-rt/lib/builtins/riscv/mulsi3.S
copy to compiler-rt/lib/builtins/riscv/int_mul_impl.inc
--- a/compiler-rt/lib/builtins/riscv/mulsi3.S
+++ b/compiler-rt/lib/builtins/riscv/int_mul_impl.inc
@@ -1,18 +1,22 @@
-//===--- mulsi3.S - Integer multiplication routines routines ---===//
+//===-- int_mul_impl.inc - Integer multiplication -------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
+//
+// Helpers used by __mulsi3, __muldi3.
+//
+//===----------------------------------------------------------------------===//
 
-#if !defined(__riscv_mul) && __riscv_xlen == 32
+#if !defined(__riscv_mul)
 	.text
 	.align 2
 
-	.globl __mulsi3
-	.type  __mulsi3, @function
-__mulsi3:
+	.globl __mulxi3
+	.type  __mulxi3, @function
+__mulxi3:
 	mv     a2, a0
 	mv     a0, zero
 .L1:
diff --git a/compiler-rt/lib/builtins/riscv/muldi3.S b/compiler-rt/lib/builtins/riscv/muldi3.S
new file mode 100644
--- /dev/null
+++ b/compiler-rt/lib/builtins/riscv/muldi3.S
@@ -0,0 +1,11 @@
+//===--- muldi3.S - Integer multiplication routines -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#if __riscv_xlen == 64
+#define __mulxi3 __muldi3
+#include "int_mul_impl.inc"
+#endif
diff --git a/compiler-rt/lib/builtins/riscv/mulsi3.S b/compiler-rt/lib/builtins/riscv/mulsi3.S
--- a/compiler-rt/lib/builtins/riscv/mulsi3.S
+++ b/compiler-rt/lib/builtins/riscv/mulsi3.S
@@ -1,4 +1,4 @@
-//===--- mulsi3.S - Integer multiplication routines routines ---===//
+//===--- mulsi3.S - Integer multiplication routines -----------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -6,22 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#if !defined(__riscv_mul) && __riscv_xlen == 32
-	.text
-	.align 2
-
-	.globl __mulsi3
-	.type  __mulsi3, @function
-__mulsi3:
-	mv     a2, a0
-	mv     a0, zero
-.L1:
-	andi   a3, a1, 1
-	beqz   a3, .L2
-	add    a0, a0, a2
-.L2:
-	srli   a1, a1, 1
-	slli   a2, a2, 1
-	bnez   a1, .L1
-	ret
+#if __riscv_xlen == 32
+#define __mulxi3 __mulsi3
+#include "int_mul_impl.inc"
 #endif