diff --git a/src/pkg/encoding/xml/xml.go b/src/pkg/encoding/xml/xml.go
index b473cb84584..a4cd4e29e01 100644
--- a/src/pkg/encoding/xml/xml.go
+++ b/src/pkg/encoding/xml/xml.go
@@ -29,6 +29,7 @@ import (
 type SyntaxError struct {
 	Msg  string
 	Line int
+	Byte int64 // byte offset from start of stream
 }
 
 func (e *SyntaxError) Error() string {
@@ -196,6 +197,7 @@ type Decoder struct {
 	ns             map[string]string
 	err            error
 	line           int
+	offset         int64
 	unmarshalDepth int
 }
 
@@ -859,9 +861,17 @@ func (d *Decoder) getc() (b byte, ok bool) {
 	if b == '\n' {
 		d.line++
 	}
+	d.offset++
 	return b, true
 }
 
+// InputOffset returns the input stream byte offset of the current decoder position.
+// The offset gives the location of the end of the most recently returned token
+// and the beginning of the next token.
+func (d *Decoder) InputOffset() int64 {
+	return d.offset
+}
+
 // Return saved offset.
 // If we did ungetc (nextByte >= 0), have to back up one.
 func (d *Decoder) savedOffset() int {
@@ -891,6 +901,7 @@ func (d *Decoder) ungetc(b byte) {
 		d.line--
 	}
 	d.nextByte = int(b)
+	d.offset--
 }
 
 var entity = map[string]int{
diff --git a/src/pkg/encoding/xml/xml_test.go b/src/pkg/encoding/xml/xml_test.go
index 7723ab1c9f0..be995c0d52c 100644
--- a/src/pkg/encoding/xml/xml_test.go
+++ b/src/pkg/encoding/xml/xml_test.go
@@ -170,7 +170,7 @@ var xmlInput = []string{
 func TestRawToken(t *testing.T) {
 	d := NewDecoder(strings.NewReader(testInput))
 	d.Entity = testEntity
-	testRawToken(t, d, rawTokens)
+	testRawToken(t, d, testInput, rawTokens)
 }
 
 const nonStrictInput = `
@@ -225,7 +225,7 @@ var nonStrictTokens = []Token{
 func TestNonStrictRawToken(t *testing.T) {
 	d := NewDecoder(strings.NewReader(nonStrictInput))
 	d.Strict = false
-	testRawToken(t, d, nonStrictTokens)
+	testRawToken(t, d, nonStrictInput, nonStrictTokens)
 }
 
 type downCaser struct {
@@ -254,7 +254,7 @@ func TestRawTokenAltEncoding(t *testing.T) {
 		}
 		return &downCaser{t, input.(io.ByteReader)}, nil
 	}
-	testRawToken(t, d, rawTokensAltEncoding)
+	testRawToken(t, d, testInputAltEncoding, rawTokensAltEncoding)
 }
 
 func TestRawTokenAltEncodingNoConverter(t *testing.T) {
@@ -280,9 +280,12 @@ func TestRawTokenAltEncodingNoConverter(t *testing.T) {
 	}
 }
 
-func testRawToken(t *testing.T, d *Decoder, rawTokens []Token) {
+func testRawToken(t *testing.T, d *Decoder, raw string, rawTokens []Token) {
+	lastEnd := int64(0)
 	for i, want := range rawTokens {
+		start := d.InputOffset()
 		have, err := d.RawToken()
+		end := d.InputOffset()
 		if err != nil {
 			t.Fatalf("token %d: unexpected error: %s", i, err)
 		}
@@ -300,6 +303,26 @@ func testRawToken(t *testing.T, d *Decoder, rawTokens []Token) {
 			}
 			t.Errorf("token %d = %s, want %s", i, shave, swant)
 		}
+
+		// Check that InputOffset returned actual token.
+		switch {
+		case start < lastEnd:
+			t.Errorf("token %d: position [%d,%d) for %T is before previous token", i, start, end, have)
+		case start >= end:
+			// Special case: EndElement can be synthesized.
+			if start == end && end == lastEnd {
+				break
+			}
+			t.Errorf("token %d: position [%d,%d) for %T is empty", i, start, end, have)
+		case end > int64(len(raw)):
+			t.Errorf("token %d: position [%d,%d) for %T extends beyond input", i, start, end, have)
+		default:
+			text := raw[start:end]
+			if strings.ContainsAny(text, "<>") && (!strings.HasPrefix(text, "<") || !strings.HasSuffix(text, ">")) {
+				t.Errorf("token %d: misaligned raw token %#q for %T", i, text, have)
+			}
+		}
+		lastEnd = end
 	}
 }