diff --git a/src/internal/bytealg/compare_generic.go b/src/internal/bytealg/compare_generic.go
index eaea168f2d..c5853f503f 100644
--- a/src/internal/bytealg/compare_generic.go
+++ b/src/internal/bytealg/compare_generic.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !386 && !amd64 && !s390x && !arm && !arm64 && !ppc64 && !ppc64le && !mips && !mipsle && !wasm && !mips64 && !mips64le
+//go:build !386 && !amd64 && !s390x && !arm && !arm64 && !ppc64 && !ppc64le && !mips && !mipsle && !wasm && !mips64 && !mips64le && !riscv64
 
 package bytealg
 
diff --git a/src/internal/bytealg/compare_native.go b/src/internal/bytealg/compare_native.go
index 21ff8fe786..ad0fcd7660 100644
--- a/src/internal/bytealg/compare_native.go
+++ b/src/internal/bytealg/compare_native.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build 386 || amd64 || s390x || arm || arm64 || ppc64 || ppc64le || mips || mipsle || wasm || mips64 || mips64le
+//go:build 386 || amd64 || s390x || arm || arm64 || ppc64 || ppc64le || mips || mipsle || wasm || mips64 || mips64le || riscv64
 
 package bytealg
 
diff --git a/src/internal/bytealg/compare_riscv64.s b/src/internal/bytealg/compare_riscv64.s
new file mode 100644
index 0000000000..0dc62515a1
--- /dev/null
+++ b/src/internal/bytealg/compare_riscv64.s
@@ -0,0 +1,185 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "go_asm.h"
+#include "textflag.h"
+
+TEXT ·Compare(SB),NOSPLIT|NOFRAME,$0-56
+	MOV	a_base+0(FP), X5
+	MOV	a_len+8(FP), X6
+	MOV	b_base+24(FP), X7
+	MOV	b_len+32(FP), X8
+	MOV	$ret+48(FP), X9
+	JMP	compare<>(SB)
+
+TEXT runtime·cmpstring(SB),NOSPLIT|NOFRAME,$0-40
+	MOV	a_base+0(FP), X5
+	MOV	a_len+8(FP), X6
+	MOV	b_base+16(FP), X7
+	MOV	b_len+24(FP), X8
+	MOV	$ret+32(FP), X9
+	JMP	compare<>(SB)
+
+// On entry:
+// X5 points to start of a
+// X6 length of a
+// X7 points to start of b
+// X8 length of b
+// X9 points to the address to store the return value (-1/0/1)
+TEXT compare<>(SB),NOSPLIT|NOFRAME,$0
+	BEQ	X5, X7, cmp_len
+
+	MOV	X6, X10
+	BGE	X8, X10, use_a_len // X10 = min(len(a), len(b))
+	MOV	X8, X10
+use_a_len:
+	BEQZ	X10, cmp_len
+
+	MOV	$32, X11
+	BLT	X10, X11, loop4_check
+
+	// Check alignment - if alignment differs we have to do one byte at a time.
+	AND	$3, X5, X12
+	AND	$3, X7, X13
+	BNE	X12, X13, loop4_check
+	BEQZ	X12, loop32_check
+
+	// Check one byte at a time until we reach 8 byte alignment.
+	SUB	X12, X10, X10
+align:
+	ADD	$-1, X12
+	MOVBU	0(X5), X13
+	MOVBU	0(X7), X14
+	BNE	X13, X14, cmp
+	ADD	$1, X5
+	ADD	$1, X7
+	BNEZ	X12, align
+
+loop32_check:
+	MOV	$32, X12
+	BLT	X10, X12, loop16_check
+loop32:
+	MOV	0(X5), X15
+	MOV	0(X7), X16
+	MOV	8(X5), X17
+	MOV	8(X7), X18
+	BEQ	X15, X16, loop32a
+	JMP	cmp8a
+loop32a:
+	BEQ	X17, X18, loop32b
+	JMP	cmp8b
+loop32b:
+	MOV	16(X5), X15
+	MOV	16(X7), X16
+	MOV	24(X5), X17
+	MOV	24(X7), X18
+	BEQ	X15, X16, loop32c
+	JMP	cmp8a
+loop32c:
+	BEQ	X17, X18, loop32d
+	JMP	cmp8b
+loop32d:
+	ADD	$32, X5
+	ADD	$32, X7
+	ADD	$-32, X10
+	BGE	X10, X12, loop32
+	BEQZ	X10, cmp_len
+
+loop16_check:
+	MOV	$16, X11
+	BLT	X10, X11, loop4_check
+loop16:
+	MOV	0(X5), X15
+	MOV	0(X7), X16
+	MOV	8(X5), X17
+	MOV	8(X7), X18
+	BEQ	X15, X16, loop16a
+	JMP	cmp8a
+loop16a:
+	BEQ	X17, X18, loop16b
+	JMP	cmp8b
+loop16b:
+	ADD	$16, X5
+	ADD	$16, X7
+	ADD	$-16, X10
+	BGE	X10, X11, loop16
+	BEQZ	X10, cmp_len
+
+loop4_check:
+	MOV	$4, X11
+	BLT	X10, X11, loop1
+loop4:
+	MOVBU	0(X5), X13
+	MOVBU	0(X7), X14
+	MOVBU	1(X5), X15
+	MOVBU	1(X7), X16
+	BEQ	X13, X14, loop4a
+	SLTU	X14, X13, X10
+	SLTU	X13, X14, X11
+	JMP	cmp_ret
+loop4a:
+	BEQ	X15, X16, loop4b
+	SLTU	X16, X15, X10
+	SLTU	X15, X16, X11
+	JMP	cmp_ret
+loop4b:
+	MOVBU	2(X5), X21
+	MOVBU	2(X7), X22
+	MOVBU	3(X5), X23
+	MOVBU	3(X7), X24
+	BEQ	X21, X22, loop4c
+	SLTU	X22, X21, X10
+	SLTU	X21, X22, X11
+	JMP	cmp_ret
+loop4c:
+	BEQ	X23, X24, loop4d
+	SLTU	X24, X23, X10
+	SLTU	X23, X24, X11
+	JMP	cmp_ret
+loop4d:
+	ADD	$4, X5
+	ADD	$4, X7
+	ADD	$-4, X10
+	BGE	X10, X11, loop4
+
+loop1:
+	BEQZ	X10, cmp_len
+	MOVBU	0(X5), X13
+	MOVBU	0(X7), X14
+	BNE	X13, X14, cmp
+	ADD	$1, X5
+	ADD	$1, X7
+	ADD	$-1, X10
+	JMP	loop1
+
+	// Compare 8 bytes of memory in X15/X16 that are known to differ.
+cmp8a:
+	MOV	$0xff, X19
+cmp8a_loop:
+	AND	X15, X19, X13
+	AND	X16, X19, X14
+	BNE	X13, X14, cmp
+	SLLI	$8, X19
+	JMP	cmp8a_loop
+
+	// Compare 8 bytes of memory in X17/X18 that are known to differ.
+cmp8b:
+	MOV	$0xff, X19
+cmp8b_loop:
+	AND	X17, X19, X13
+	AND	X18, X19, X14
+	BNE	X13, X14, cmp
+	SLLI	$8, X19
+	JMP	cmp8b_loop
+
+cmp_len:
+	MOV	X6, X13
+	MOV	X8, X14
+cmp:
+	SLTU	X14, X13, X10
+	SLTU	X13, X14, X11
+cmp_ret:
+	SUB	X10, X11, X12
+	MOV	X12, (X9)
+	RET