diff --git a/src/cmd/compile/internal/ssa/_gen/AMD64.rules b/src/cmd/compile/internal/ssa/_gen/AMD64.rules
index 7840600ef6..090ad90c64 100644
--- a/src/cmd/compile/internal/ssa/_gen/AMD64.rules
+++ b/src/cmd/compile/internal/ssa/_gen/AMD64.rules
@@ -1449,6 +1449,10 @@
 (TESTW (MOVLconst [c]) x) => (TESTWconst [int16(c)] x)
 (TESTB (MOVLconst [c]) x) => (TESTBconst [int8(c)] x)
 
+// shorten bitwise AND/TESTQ if upper 32 bits are known to be zero.
+(ANDQ x y) && (zeroUpper32Bits(x, 3) || zeroUpper32Bits(y, 3)) => (ANDL x y)
+(TESTQ x y) && (zeroUpper32Bits(x, 3) || zeroUpper32Bits(y, 3)) => (TESTL x y)
+
 // TEST %reg,%reg is shorter than CMP
 (CMPQconst x [0]) => (TESTQ x x)
 (CMPLconst x [0]) => (TESTL x x)
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index 5cf5425fdc..0c87a4b1b5 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -3094,6 +3094,22 @@ func rewriteValueAMD64_OpAMD64ANDQ(v *Value) bool {
 		v.copyOf(x)
 		return true
 	}
+	// match: (ANDQ x y)
+	// cond: (zeroUpper32Bits(x, 3) || zeroUpper32Bits(y, 3))
+	// result: (ANDL x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			x := v_0
+			y := v_1
+			if !(zeroUpper32Bits(x, 3) || zeroUpper32Bits(y, 3)) {
+				continue
+			}
+			v.reset(OpAMD64ANDL)
+			v.AddArg2(x, y)
+			return true
+		}
+		break
+	}
 	// match: (ANDQ x l:(MOVQload [off] {sym} ptr mem))
 	// cond: canMergeLoadClobber(v, l, x) && clobber(l)
 	// result: (ANDQload x [off] {sym} ptr mem)
@@ -22702,6 +22718,22 @@ func rewriteValueAMD64_OpAMD64TESTQ(v *Value) bool {
 		}
 		break
 	}
+	// match: (TESTQ x y)
+	// cond: (zeroUpper32Bits(x, 3) || zeroUpper32Bits(y, 3))
+	// result: (TESTL x y)
+	for {
+		for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
+			x := v_0
+			y := v_1
+			if !(zeroUpper32Bits(x, 3) || zeroUpper32Bits(y, 3)) {
+				continue
+			}
+			v.reset(OpAMD64TESTL)
+			v.AddArg2(x, y)
+			return true
+		}
+		break
+	}
 	// match: (TESTQ l:(MOVQload {sym} [off] ptr mem) l2)
 	// cond: l == l2 && l.Uses == 2 && clobber(l)
 	// result: @l.Block (CMPQconstload {sym} [makeValAndOff(0, off)] ptr mem)