diff --git a/arch/x86/crypto/chacha20-ssse3-x86_64.S b/arch/x86/crypto/chacha20-ssse3-x86_64.S
index 512a2b500fd1..98d130b5e4ab 100644
--- a/arch/x86/crypto/chacha20-ssse3-x86_64.S
+++ b/arch/x86/crypto/chacha20-ssse3-x86_64.S
@@ -25,12 +25,13 @@ CTRINC:	.octa 0x00000003000000020000000100000000
 
 ENTRY(chacha20_block_xor_ssse3)
 	# %rdi: Input state matrix, s
-	# %rsi: 1 data block output, o
-	# %rdx: 1 data block input, i
+	# %rsi: up to 1 data block output, o
+	# %rdx: up to 1 data block input, i
+	# %rcx: input/output length in bytes
 
 	# This function encrypts one ChaCha20 block by loading the state matrix
 	# in four SSE registers. It performs matrix operation on four words in
-	# parallel, but requireds shuffling to rearrange the words after each
+	# parallel, but requires shuffling to rearrange the words after each
 	# round. 8/16-bit word rotation is done with the slightly better
 	# performing SSSE3 byte shuffling, 7/12-bit word rotation uses
 	# traditional shift+OR.
@@ -48,7 +49,8 @@ ENTRY(chacha20_block_xor_ssse3)
 	movdqa		ROT8(%rip),%xmm4
 	movdqa		ROT16(%rip),%xmm5
 
-	mov	$10,%ecx
+	mov		%rcx,%rax
+	mov		$10,%ecx
 
 .Ldoubleround:
 
@@ -122,27 +124,69 @@ ENTRY(chacha20_block_xor_ssse3)
 	jnz		.Ldoubleround
 
 	# o0 = i0 ^ (x0 + s0)
-	movdqu		0x00(%rdx),%xmm4
 	paddd		%xmm8,%xmm0
+	cmp		$0x10,%rax
+	jl		.Lxorpart
+	movdqu		0x00(%rdx),%xmm4
 	pxor		%xmm4,%xmm0
 	movdqu		%xmm0,0x00(%rsi)
 	# o1 = i1 ^ (x1 + s1)
-	movdqu		0x10(%rdx),%xmm5
 	paddd		%xmm9,%xmm1
-	pxor		%xmm5,%xmm1
-	movdqu		%xmm1,0x10(%rsi)
+	movdqa		%xmm1,%xmm0
+	cmp		$0x20,%rax
+	jl		.Lxorpart
+	movdqu		0x10(%rdx),%xmm0
+	pxor		%xmm1,%xmm0
+	movdqu		%xmm0,0x10(%rsi)
 	# o2 = i2 ^ (x2 + s2)
-	movdqu		0x20(%rdx),%xmm6
 	paddd		%xmm10,%xmm2
-	pxor		%xmm6,%xmm2
-	movdqu		%xmm2,0x20(%rsi)
+	movdqa		%xmm2,%xmm0
+	cmp		$0x30,%rax
+	jl		.Lxorpart
+	movdqu		0x20(%rdx),%xmm0
+	pxor		%xmm2,%xmm0
+	movdqu		%xmm0,0x20(%rsi)
 	# o3 = i3 ^ (x3 + s3)
-	movdqu		0x30(%rdx),%xmm7
 	paddd		%xmm11,%xmm3
-	pxor		%xmm7,%xmm3
-	movdqu		%xmm3,0x30(%rsi)
+	movdqa		%xmm3,%xmm0
+	cmp		$0x40,%rax
+	jl		.Lxorpart
+	movdqu		0x30(%rdx),%xmm0
+	pxor		%xmm3,%xmm0
+	movdqu		%xmm0,0x30(%rsi)
 
+.Ldone:
 	ret
+
+.Lxorpart:
+	# xor remaining bytes from partial register into output
+	mov		%rax,%r9
+	and		$0x0f,%r9
+	jz		.Ldone
+	and		$~0x0f,%rax
+
+	mov		%rsi,%r11
+
+	lea		8(%rsp),%r10
+	sub		$0x10,%rsp
+	and		$~31,%rsp
+
+	lea		(%rdx,%rax),%rsi
+	mov		%rsp,%rdi
+	mov		%r9,%rcx
+	rep movsb
+
+	pxor		0x00(%rsp),%xmm0
+	movdqa		%xmm0,0x00(%rsp)
+
+	mov		%rsp,%rsi
+	lea		(%r11,%rax),%rdi
+	mov		%r9,%rcx
+	rep movsb
+
+	lea		-8(%r10),%rsp
+	jmp		.Ldone
+
 ENDPROC(chacha20_block_xor_ssse3)
 
 ENTRY(chacha20_4block_xor_ssse3)
diff --git a/arch/x86/crypto/chacha20_glue.c b/arch/x86/crypto/chacha20_glue.c
index dce7c5d39c2f..cc4571736ce8 100644
--- a/arch/x86/crypto/chacha20_glue.c
+++ b/arch/x86/crypto/chacha20_glue.c
@@ -19,7 +19,8 @@
 
 #define CHACHA20_STATE_ALIGN 16
 
-asmlinkage void chacha20_block_xor_ssse3(u32 *state, u8 *dst, const u8 *src);
+asmlinkage void chacha20_block_xor_ssse3(u32 *state, u8 *dst, const u8 *src,
+					 unsigned int len);
 asmlinkage void chacha20_4block_xor_ssse3(u32 *state, u8 *dst, const u8 *src);
 #ifdef CONFIG_AS_AVX2
 asmlinkage void chacha20_8block_xor_avx2(u32 *state, u8 *dst, const u8 *src);
@@ -29,8 +30,6 @@ static bool chacha20_use_avx2;
 static void chacha20_dosimd(u32 *state, u8 *dst, const u8 *src,
 			    unsigned int bytes)
 {
-	u8 buf[CHACHA20_BLOCK_SIZE];
-
 #ifdef CONFIG_AS_AVX2
 	if (chacha20_use_avx2) {
 		while (bytes >= CHACHA20_BLOCK_SIZE * 8) {
@@ -50,16 +49,14 @@ static void chacha20_dosimd(u32 *state, u8 *dst, const u8 *src,
 		state[12] += 4;
 	}
 	while (bytes >= CHACHA20_BLOCK_SIZE) {
-		chacha20_block_xor_ssse3(state, dst, src);
+		chacha20_block_xor_ssse3(state, dst, src, bytes);
 		bytes -= CHACHA20_BLOCK_SIZE;
 		src += CHACHA20_BLOCK_SIZE;
 		dst += CHACHA20_BLOCK_SIZE;
 		state[12]++;
 	}
 	if (bytes) {
-		memcpy(buf, src, bytes);
-		chacha20_block_xor_ssse3(state, buf, buf);
-		memcpy(dst, buf, bytes);
+		chacha20_block_xor_ssse3(state, dst, src, bytes);
 	}
 }