diff --git a/src/cmd/compile/internal/ssa/gen/AMD64.rules b/src/cmd/compile/internal/ssa/gen/AMD64.rules
index bab9cee88c..7b03034bb7 100644
--- a/src/cmd/compile/internal/ssa/gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/gen/AMD64.rules
@@ -1970,15 +1970,15 @@
   && clobber(x)
   => (MOVQstore [i] {s} p0 w0 mem)
 
-(MOVBstore [7] p1 (SHRQconst [56] w)
-  x1:(MOVWstore [5] p1 (SHRQconst [40] w)
-  x2:(MOVLstore [1] p1 (SHRQconst [8] w)
-  x3:(MOVBstore p1 w mem))))
+(MOVBstore [7] {s} p1 (SHRQconst [56] w)
+  x1:(MOVWstore [5] {s} p1 (SHRQconst [40] w)
+  x2:(MOVLstore [1] {s} p1 (SHRQconst [8] w)
+  x3:(MOVBstore [0] {s} p1 w mem))))
   && x1.Uses == 1
   && x2.Uses == 1
   && x3.Uses == 1
   && clobber(x1, x2, x3)
-  => (MOVQstore p1 w mem)
+  => (MOVQstore {s} p1 w mem)
 
 (MOVBstore [i] {s} p
   x1:(MOVBload [j] {s2} p2 mem)
diff --git a/src/cmd/compile/internal/ssa/gen/S390X.rules b/src/cmd/compile/internal/ssa/gen/S390X.rules
index e4a1cd6981..1f75f78a71 100644
--- a/src/cmd/compile/internal/ssa/gen/S390X.rules
+++ b/src/cmd/compile/internal/ssa/gen/S390X.rules
@@ -1422,15 +1422,15 @@
   && clobber(x)
   => (MOVDBRstore [i-4] {s} p w0 mem)
 
-(MOVBstore [7] p1 (SRDconst w)
-  x1:(MOVHBRstore [5] p1 (SRDconst w)
-  x2:(MOVWBRstore [1] p1 (SRDconst w)
-  x3:(MOVBstore p1 w mem))))
+(MOVBstore [7] {s} p1 (SRDconst w)
+  x1:(MOVHBRstore [5] {s} p1 (SRDconst w)
+  x2:(MOVWBRstore [1] {s} p1 (SRDconst w)
+  x3:(MOVBstore [0] {s} p1 w mem))))
   && x1.Uses == 1
   && x2.Uses == 1
   && x3.Uses == 1
   && clobber(x1, x2, x3)
-  => (MOVDBRstore p1 w mem)
+  => (MOVDBRstore {s} p1 w mem)
 
 // Combining byte loads into larger (unaligned) loads.
 
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index 52d0fd095d..8da3b28b5c 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -11415,20 +11415,21 @@ func rewriteValueAMD64_OpAMD64MOVBstore(v *Value) bool {
 		v.AddArg3(p0, w0, mem)
 		return true
 	}
-	// match: (MOVBstore [7] p1 (SHRQconst [56] w) x1:(MOVWstore [5] p1 (SHRQconst [40] w) x2:(MOVLstore [1] p1 (SHRQconst [8] w) x3:(MOVBstore p1 w mem))))
+	// match: (MOVBstore [7] {s} p1 (SHRQconst [56] w) x1:(MOVWstore [5] {s} p1 (SHRQconst [40] w) x2:(MOVLstore [1] {s} p1 (SHRQconst [8] w) x3:(MOVBstore [0] {s} p1 w mem))))
 	// cond: x1.Uses == 1 && x2.Uses == 1 && x3.Uses == 1 && clobber(x1, x2, x3)
-	// result: (MOVQstore p1 w mem)
+	// result: (MOVQstore {s} p1 w mem)
 	for {
 		if auxIntToInt32(v.AuxInt) != 7 {
 			break
 		}
+		s := auxToSym(v.Aux)
 		p1 := v_0
 		if v_1.Op != OpAMD64SHRQconst || auxIntToInt8(v_1.AuxInt) != 56 {
 			break
 		}
 		w := v_1.Args[0]
 		x1 := v_2
-		if x1.Op != OpAMD64MOVWstore || auxIntToInt32(x1.AuxInt) != 5 {
+		if x1.Op != OpAMD64MOVWstore || auxIntToInt32(x1.AuxInt) != 5 || auxToSym(x1.Aux) != s {
 			break
 		}
 		_ = x1.Args[2]
@@ -11440,7 +11441,7 @@ func rewriteValueAMD64_OpAMD64MOVBstore(v *Value) bool {
 			break
 		}
 		x2 := x1.Args[2]
-		if x2.Op != OpAMD64MOVLstore || auxIntToInt32(x2.AuxInt) != 1 {
+		if x2.Op != OpAMD64MOVLstore || auxIntToInt32(x2.AuxInt) != 1 || auxToSym(x2.Aux) != s {
 			break
 		}
 		_ = x2.Args[2]
@@ -11452,7 +11453,7 @@ func rewriteValueAMD64_OpAMD64MOVBstore(v *Value) bool {
 			break
 		}
 		x3 := x2.Args[2]
-		if x3.Op != OpAMD64MOVBstore {
+		if x3.Op != OpAMD64MOVBstore || auxIntToInt32(x3.AuxInt) != 0 || auxToSym(x3.Aux) != s {
 			break
 		}
 		mem := x3.Args[2]
@@ -11460,6 +11461,7 @@ func rewriteValueAMD64_OpAMD64MOVBstore(v *Value) bool {
 			break
 		}
 		v.reset(OpAMD64MOVQstore)
+		v.Aux = symToAux(s)
 		v.AddArg3(p1, w, mem)
 		return true
 	}
diff --git a/src/cmd/compile/internal/ssa/rewriteS390X.go b/src/cmd/compile/internal/ssa/rewriteS390X.go
index e0a5ff4cbb..85260dace8 100644
--- a/src/cmd/compile/internal/ssa/rewriteS390X.go
+++ b/src/cmd/compile/internal/ssa/rewriteS390X.go
@@ -8883,20 +8883,21 @@ func rewriteValueS390X_OpS390XMOVBstore(v *Value) bool {
 		v.AddArg3(p, w0, mem)
 		return true
 	}
-	// match: (MOVBstore [7] p1 (SRDconst w) x1:(MOVHBRstore [5] p1 (SRDconst w) x2:(MOVWBRstore [1] p1 (SRDconst w) x3:(MOVBstore p1 w mem))))
+	// match: (MOVBstore [7] {s} p1 (SRDconst w) x1:(MOVHBRstore [5] {s} p1 (SRDconst w) x2:(MOVWBRstore [1] {s} p1 (SRDconst w) x3:(MOVBstore [0] {s} p1 w mem))))
 	// cond: x1.Uses == 1 && x2.Uses == 1 && x3.Uses == 1 && clobber(x1, x2, x3)
-	// result: (MOVDBRstore p1 w mem)
+	// result: (MOVDBRstore {s} p1 w mem)
 	for {
 		if auxIntToInt32(v.AuxInt) != 7 {
 			break
 		}
+		s := auxToSym(v.Aux)
 		p1 := v_0
 		if v_1.Op != OpS390XSRDconst {
 			break
 		}
 		w := v_1.Args[0]
 		x1 := v_2
-		if x1.Op != OpS390XMOVHBRstore || auxIntToInt32(x1.AuxInt) != 5 {
+		if x1.Op != OpS390XMOVHBRstore || auxIntToInt32(x1.AuxInt) != 5 || auxToSym(x1.Aux) != s {
 			break
 		}
 		_ = x1.Args[2]
@@ -8908,7 +8909,7 @@ func rewriteValueS390X_OpS390XMOVBstore(v *Value) bool {
 			break
 		}
 		x2 := x1.Args[2]
-		if x2.Op != OpS390XMOVWBRstore || auxIntToInt32(x2.AuxInt) != 1 {
+		if x2.Op != OpS390XMOVWBRstore || auxIntToInt32(x2.AuxInt) != 1 || auxToSym(x2.Aux) != s {
 			break
 		}
 		_ = x2.Args[2]
@@ -8920,7 +8921,7 @@ func rewriteValueS390X_OpS390XMOVBstore(v *Value) bool {
 			break
 		}
 		x3 := x2.Args[2]
-		if x3.Op != OpS390XMOVBstore {
+		if x3.Op != OpS390XMOVBstore || auxIntToInt32(x3.AuxInt) != 0 || auxToSym(x3.Aux) != s {
 			break
 		}
 		mem := x3.Args[2]
@@ -8928,6 +8929,7 @@ func rewriteValueS390X_OpS390XMOVBstore(v *Value) bool {
 			break
 		}
 		v.reset(OpS390XMOVDBRstore)
+		v.Aux = symToAux(s)
 		v.AddArg3(p1, w, mem)
 		return true
 	}
diff --git a/test/fixedbugs/issue44823.go b/test/fixedbugs/issue44823.go
new file mode 100644
index 0000000000..85811df67d
--- /dev/null
+++ b/test/fixedbugs/issue44823.go
@@ -0,0 +1,26 @@
+// run
+
+// Copyright 2021 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.
+
+// Issue 44823: miscompilation with store combining.
+
+package main
+
+import "encoding/binary"
+
+//go:noinline
+func Id(a [8]byte) (x [8]byte) {
+	binary.LittleEndian.PutUint64(x[:], binary.LittleEndian.Uint64(a[:]))
+	return
+}
+
+var a = [8]byte{1, 2, 3, 4, 5, 6, 7, 8}
+
+func main() {
+	x := Id(a)
+	if x != a {
+		panic("FAIL")
+	}
+}