diff --git a/src/cmd/compile/internal/gc/asm_test.go b/src/cmd/compile/internal/gc/asm_test.go
index bfd1f8a784d..232f39d6b48 100644
--- a/src/cmd/compile/internal/gc/asm_test.go
+++ b/src/cmd/compile/internal/gc/asm_test.go
@@ -261,6 +261,11 @@ var allAsmTests = []*asmTests{
 		os:    "linux",
 		tests: linuxPPC64LETests,
 	},
+	{
+		arch:  "amd64",
+		os:    "plan9",
+		tests: plan9AMD64Tests,
+	},
 }
 
 var linuxAMD64Tests = []*asmTest{
@@ -2126,6 +2131,34 @@ var linuxPPC64LETests = []*asmTest{
 	},
 }
 
+var plan9AMD64Tests = []*asmTest{
+	// We should make sure that the compiler doesn't generate floating point
+	// instructions for non-float operations on Plan 9, because floating point
+	// operations are not allowed in the note handler.
+	// Array zeroing.
+	{
+		`
+		func $() [16]byte {
+			var a [16]byte
+			return a
+		}
+		`,
+		[]string{"\tMOVQ\t\\$0, \"\""},
+		[]string{},
+	},
+	// Array copy.
+	{
+		`
+		func $(a [16]byte) (b [16]byte) {
+			b = a
+			return
+		}
+		`,
+		[]string{"\tMOVQ\t\"\"\\.a\\+[0-9]+\\(SP\\), (AX|CX)", "\tMOVQ\t(AX|CX), \"\"\\.b\\+[0-9]+\\(SP\\)"},
+		[]string{},
+	},
+}
+
 // TestLineNumber checks to make sure the generated assembly has line numbers
 // see issue #16214
 func TestLineNumber(t *testing.T) {
diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index 0e19e5970a5..ff1b97b0a4c 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -319,7 +319,10 @@
 (Move [2] dst src mem) -> (MOVWstore dst (MOVWload src mem) mem)
 (Move [4] dst src mem) -> (MOVLstore dst (MOVLload src mem) mem)
 (Move [8] dst src mem) -> (MOVQstore dst (MOVQload src mem) mem)
-(Move [16] dst src mem) -> (MOVOstore dst (MOVOload src mem) mem)
+(Move [16] dst src mem) && config.useSSE -> (MOVOstore dst (MOVOload src mem) mem)
+(Move [16] dst src mem) && !config.useSSE ->
+	(MOVQstore [8] dst (MOVQload [8] src mem)
+		(MOVQstore dst (MOVQload src mem) mem))
 (Move [3] dst src mem) ->
 	(MOVBstore [2] dst (MOVBload [2] src mem)
 		(MOVWstore dst (MOVWload src mem) mem))
@@ -344,11 +347,18 @@
 		(OffPtr <src.Type> src [s%16])
 		(MOVQstore dst (MOVQload src mem) mem))
 (Move [s] dst src mem)
-	&& s > 16 && s%16 != 0 && s%16 > 8 ->
+	&& s > 16 && s%16 != 0 && s%16 > 8 && config.useSSE ->
 	(Move [s-s%16]
 		(OffPtr <dst.Type> dst [s%16])
 		(OffPtr <src.Type> src [s%16])
 		(MOVOstore dst (MOVOload src mem) mem))
+(Move [s] dst src mem)
+	&& s > 16 && s%16 != 0 && s%16 > 8 && !config.useSSE ->
+	(Move [s-s%16]
+		(OffPtr <dst.Type> dst [s%16])
+		(OffPtr <src.Type> src [s%16])
+		(MOVQstore [8] dst (MOVQload [8] src mem)
+			(MOVQstore dst (MOVQload src mem) mem)))
 
 // Medium copying uses a duff device.
 (Move [s] dst src mem)
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index e2971696bb3..399afa6ef9b 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -41824,6 +41824,8 @@ func rewriteValueAMD64_OpMod8u_0(v *Value) bool {
 func rewriteValueAMD64_OpMove_0(v *Value) bool {
 	b := v.Block
 	_ = b
+	config := b.Func.Config
+	_ = config
 	typ := &b.Func.Config.Types
 	_ = typ
 	// match: (Move [0] _ _ mem)
@@ -41921,7 +41923,7 @@ func rewriteValueAMD64_OpMove_0(v *Value) bool {
 		return true
 	}
 	// match: (Move [16] dst src mem)
-	// cond:
+	// cond: config.useSSE
 	// result: (MOVOstore dst (MOVOload src mem) mem)
 	for {
 		if v.AuxInt != 16 {
@@ -41931,6 +41933,9 @@ func rewriteValueAMD64_OpMove_0(v *Value) bool {
 		dst := v.Args[0]
 		src := v.Args[1]
 		mem := v.Args[2]
+		if !(config.useSSE) {
+			break
+		}
 		v.reset(OpAMD64MOVOstore)
 		v.AddArg(dst)
 		v0 := b.NewValue0(v.Pos, OpAMD64MOVOload, types.TypeInt128)
@@ -41940,6 +41945,38 @@ func rewriteValueAMD64_OpMove_0(v *Value) bool {
 		v.AddArg(mem)
 		return true
 	}
+	// match: (Move [16] dst src mem)
+	// cond: !config.useSSE
+	// result: (MOVQstore [8] dst (MOVQload [8] src mem) 		(MOVQstore dst (MOVQload src mem) mem))
+	for {
+		if v.AuxInt != 16 {
+			break
+		}
+		_ = v.Args[2]
+		dst := v.Args[0]
+		src := v.Args[1]
+		mem := v.Args[2]
+		if !(!config.useSSE) {
+			break
+		}
+		v.reset(OpAMD64MOVQstore)
+		v.AuxInt = 8
+		v.AddArg(dst)
+		v0 := b.NewValue0(v.Pos, OpAMD64MOVQload, typ.UInt64)
+		v0.AuxInt = 8
+		v0.AddArg(src)
+		v0.AddArg(mem)
+		v.AddArg(v0)
+		v1 := b.NewValue0(v.Pos, OpAMD64MOVQstore, types.TypeMem)
+		v1.AddArg(dst)
+		v2 := b.NewValue0(v.Pos, OpAMD64MOVQload, typ.UInt64)
+		v2.AddArg(src)
+		v2.AddArg(mem)
+		v1.AddArg(v2)
+		v1.AddArg(mem)
+		v.AddArg(v1)
+		return true
+	}
 	// match: (Move [3] dst src mem)
 	// cond:
 	// result: (MOVBstore [2] dst (MOVBload [2] src mem) 		(MOVWstore dst (MOVWload src mem) mem))
@@ -42027,6 +42064,15 @@ func rewriteValueAMD64_OpMove_0(v *Value) bool {
 		v.AddArg(v1)
 		return true
 	}
+	return false
+}
+func rewriteValueAMD64_OpMove_10(v *Value) bool {
+	b := v.Block
+	_ = b
+	config := b.Func.Config
+	_ = config
+	typ := &b.Func.Config.Types
+	_ = typ
 	// match: (Move [7] dst src mem)
 	// cond:
 	// result: (MOVLstore [3] dst (MOVLload [3] src mem) 		(MOVLstore dst (MOVLload src mem) mem))
@@ -42056,15 +42102,6 @@ func rewriteValueAMD64_OpMove_0(v *Value) bool {
 		v.AddArg(v1)
 		return true
 	}
-	return false
-}
-func rewriteValueAMD64_OpMove_10(v *Value) bool {
-	b := v.Block
-	_ = b
-	config := b.Func.Config
-	_ = config
-	typ := &b.Func.Config.Types
-	_ = typ
 	// match: (Move [s] dst src mem)
 	// cond: s > 8 && s < 16
 	// result: (MOVQstore [s-8] dst (MOVQload [s-8] src mem) 		(MOVQstore dst (MOVQload src mem) mem))
@@ -42128,7 +42165,7 @@ func rewriteValueAMD64_OpMove_10(v *Value) bool {
 		return true
 	}
 	// match: (Move [s] dst src mem)
-	// cond: s > 16 && s%16 != 0 && s%16 > 8
+	// cond: s > 16 && s%16 != 0 && s%16 > 8 && config.useSSE
 	// result: (Move [s-s%16] 		(OffPtr <dst.Type> dst [s%16]) 		(OffPtr <src.Type> src [s%16]) 		(MOVOstore dst (MOVOload src mem) mem))
 	for {
 		s := v.AuxInt
@@ -42136,7 +42173,7 @@ func rewriteValueAMD64_OpMove_10(v *Value) bool {
 		dst := v.Args[0]
 		src := v.Args[1]
 		mem := v.Args[2]
-		if !(s > 16 && s%16 != 0 && s%16 > 8) {
+		if !(s > 16 && s%16 != 0 && s%16 > 8 && config.useSSE) {
 			break
 		}
 		v.reset(OpMove)
@@ -42160,6 +42197,47 @@ func rewriteValueAMD64_OpMove_10(v *Value) bool {
 		return true
 	}
 	// match: (Move [s] dst src mem)
+	// cond: s > 16 && s%16 != 0 && s%16 > 8 && !config.useSSE
+	// result: (Move [s-s%16] 		(OffPtr <dst.Type> dst [s%16]) 		(OffPtr <src.Type> src [s%16]) 		(MOVQstore [8] dst (MOVQload [8] src mem) 			(MOVQstore dst (MOVQload src mem) mem)))
+	for {
+		s := v.AuxInt
+		_ = v.Args[2]
+		dst := v.Args[0]
+		src := v.Args[1]
+		mem := v.Args[2]
+		if !(s > 16 && s%16 != 0 && s%16 > 8 && !config.useSSE) {
+			break
+		}
+		v.reset(OpMove)
+		v.AuxInt = s - s%16
+		v0 := b.NewValue0(v.Pos, OpOffPtr, dst.Type)
+		v0.AuxInt = s % 16
+		v0.AddArg(dst)
+		v.AddArg(v0)
+		v1 := b.NewValue0(v.Pos, OpOffPtr, src.Type)
+		v1.AuxInt = s % 16
+		v1.AddArg(src)
+		v.AddArg(v1)
+		v2 := b.NewValue0(v.Pos, OpAMD64MOVQstore, types.TypeMem)
+		v2.AuxInt = 8
+		v2.AddArg(dst)
+		v3 := b.NewValue0(v.Pos, OpAMD64MOVQload, typ.UInt64)
+		v3.AuxInt = 8
+		v3.AddArg(src)
+		v3.AddArg(mem)
+		v2.AddArg(v3)
+		v4 := b.NewValue0(v.Pos, OpAMD64MOVQstore, types.TypeMem)
+		v4.AddArg(dst)
+		v5 := b.NewValue0(v.Pos, OpAMD64MOVQload, typ.UInt64)
+		v5.AddArg(src)
+		v5.AddArg(mem)
+		v4.AddArg(v5)
+		v4.AddArg(mem)
+		v2.AddArg(v4)
+		v.AddArg(v2)
+		return true
+	}
+	// match: (Move [s] dst src mem)
 	// cond: s >= 32 && s <= 16*64 && s%16 == 0 	&& !config.noDuffDevice
 	// result: (DUFFCOPY [14*(64-s/16)] dst src mem)
 	for {