diff --git a/src/cmd/asm/internal/asm/asm.go b/src/cmd/asm/internal/asm/asm.go
index 63adef271be..43085ae2568 100644
--- a/src/cmd/asm/internal/asm/asm.go
+++ b/src/cmd/asm/internal/asm/asm.go
@@ -153,6 +153,11 @@ func (p *Parser) asmText(word string, operands [][]lex.Token) {
 		p.errorf("expect two or three operands for TEXT")
 	}
 
+	// Labels are function scoped. Patch existing labels and
+	// create a new label space for this TEXT.
+	p.patch()
+	p.labels = make(map[string]*obj.Prog)
+
 	// Operand 0 is the symbol name in the form foo(SB).
 	// That means symbol plus indirect on SB and no offset.
 	nameAddr := p.address(operands[0])
@@ -219,6 +224,7 @@ func (p *Parser) asmText(word string, operands [][]lex.Token) {
 			Index: uint8(p.arch.D_NONE),
 		},
 	}
+
 	// Encoding of frameSize and argSize depends on architecture.
 	switch p.arch.Thechar {
 	case '6':
@@ -231,6 +237,7 @@ func (p *Parser) asmText(word string, operands [][]lex.Token) {
 	default:
 		p.errorf("internal error: can't encode TEXT $arg-frame")
 	}
+
 	p.append(prog, true)
 }
 
@@ -493,6 +500,7 @@ func (p *Parser) patch() {
 			p.branch(patch.prog, targetProg)
 		}
 	}
+	p.toPatch = p.toPatch[:0]
 }
 
 func (p *Parser) branch(jmp, target *obj.Prog) {
diff --git a/src/cmd/asm/internal/asm/overflow.go b/src/cmd/asm/internal/asm/overflow.go
deleted file mode 100644
index a4292011aef..00000000000
--- a/src/cmd/asm/internal/asm/overflow.go
+++ /dev/null
@@ -1,129 +0,0 @@
-// Copyright 2015 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.
-
-package asm
-
-/*
-	Tested with uint8s like this:
-
-	for a := 0; a <= 255; a++ {
-		for b := 0; b <= 127; b++ {
-			ovfl := a+b != int(uint8(a)+uint8(b))
-			if addOverflows(uint8(a), uint8(b)) != ovfl {
-				fmt.Printf("%d+%d fails\n", a, b)
-				break
-			}
-		}
-	}
-	for a := 0; a <= 255; a++ {
-		for b := 0; b <= 127; b++ {
-			ovfl := a-b != int(uint8(a)-uint8(b))
-			if subOverflows(uint8(a), uint8(b)) != ovfl {
-				fmt.Printf("%d-%d fails\n", a, b)
-				break
-			}
-		}
-	}
-	for a := 0; a <= 255; a++ {
-		for b := 0; b <= 255; b++ {
-			ovfl := a*b != int(uint8(a)*uint8(b))
-			if mulOverflows(uint8(a), uint8(b)) != ovfl {
-				fmt.Printf("%d*%d fails\n", a, b)
-			}
-		}
-	}
-	overflow := func(a, b int) bool {
-		for ; b > 0; b-- {
-			a <<= 1
-			if a >= 256 {
-				return true
-			}
-		}
-		return false
-	}
-	for a := 0; a <= 255; a++ {
-		for b := 0; b <= 255; b++ {
-			ovfl := overflow(a, b)
-			if shiftOverflows(uint8(a), uint8(b)) != ovfl {
-				fmt.Printf("%d<<%d fails\n", a, b)
-			}
-		}
-	}
-*/
-
-func addOverflows(a, b uint64) bool {
-	return a+b < a
-}
-
-func subOverflows(a, b uint64) bool {
-	return a-b > a
-}
-
-func mulOverflows(a, b uint64) bool {
-	if a <= 1 || b <= 1 {
-		return false
-	}
-	c := a * b
-	return c/b != a
-}
-
-func shiftOverflows(a, b uint64) bool {
-	c := a << b
-	return c>>b != a
-}
-
-/*
-For the record, signed overflow:
-
-const mostNegative = -(mostPositive + 1)
-const mostPositive = 1<<63 - 1
-
-func signedAddOverflows(a, b int64) bool {
-	if (a >= 0) != (b >= 0) {
-		// Different signs cannot overflow.
-		return false
-	}
-	if a >= 0 {
-		// Both are positive.
-		return a+b < 0
-	}
-	return a+b >= 0
-}
-
-func signedSubOverflows(a, b int64) bool {
-	if (a >= 0) == (b >= 0) {
-		// Same signs cannot overflow.
-		return false
-	}
-	if a >= 0 {
-		// a positive, b negative.
-		return a-b < 0
-	}
-	return a-b >= 0
-}
-
-func signedMulOverflows(a, b int64) bool {
-	if a == 0 || b == 0 || a == 1 || b == 1 {
-		return false
-	}
-	if a == mostNegative || b == mostNegative {
-		return true
-	}
-	c := a * b
-	return c/b != a
-}
-
-func signedShiftOverflows(a, b int64) bool {
-	// Avoid right shift of a negative number.
-	if a >= 0 {
-		c := a << b
-		return c>>b != a
-	}
-	// Otherwise it's negative, so we complement, which
-	// puts zeros at the top.
-	a = ^a
-	c := a << b
-	return c>>b != a
-}
-*/
diff --git a/src/cmd/asm/internal/asm/parse.go b/src/cmd/asm/internal/asm/parse.go
index be616ec0bcc..b0f6ca9f08e 100644
--- a/src/cmd/asm/internal/asm/parse.go
+++ b/src/cmd/asm/internal/asm/parse.go
@@ -360,11 +360,7 @@ func (p *Parser) expr() uint64 {
 		switch p.peek() {
 		case '+':
 			p.next()
-			x := p.term()
-			if addOverflows(x, value) {
-				p.errorf("overflow in %d+%d", value, x)
-			}
-			value += x
+			value += p.term()
 		case '-':
 			p.next()
 			value -= p.term()
@@ -408,13 +404,12 @@ func (p *Parser) term() uint64 {
 		switch p.peek() {
 		case '*':
 			p.next()
-			x := p.factor()
-			if mulOverflows(value, x) {
-				p.errorf("%d * %d overflows", value, x)
-			}
-			value *= x
+			value *= p.factor()
 		case '/':
 			p.next()
+			if value&(1<<63) != 0 {
+				p.errorf("divide with high bit set")
+			}
 			value /= p.factor()
 		case '%':
 			p.next()
@@ -425,9 +420,6 @@ func (p *Parser) term() uint64 {
 			if int64(shift) < 0 {
 				p.errorf("negative left shift %d", shift)
 			}
-			if shiftOverflows(value, shift) {
-				p.errorf("%d << %d overflows", value, shift)
-			}
 			return value << shift
 		case lex.RSH:
 			p.next()
@@ -435,6 +427,9 @@ func (p *Parser) term() uint64 {
 			if shift < 0 {
 				p.errorf("negative right shift %d", shift)
 			}
+			if shift > 0 && value&(1<<63) != 0 {
+				p.errorf("right shift with high bit set")
+			}
 			value >>= uint(shift)
 		case '&':
 			p.next()