diff --git a/frontend/dockerfile/parser/dumper/main.go b/frontend/dockerfile/parser/dumper/main.go
index 8c357f4c..6561708c 100644
--- a/frontend/dockerfile/parser/dumper/main.go
+++ b/frontend/dockerfile/parser/dumper/main.go
@@ -22,7 +22,10 @@ func main() {
 			panic(err)
 		}
 
-		ast, err := parser.Parse(f)
+		d := parser.Directive{LookingForDirectives: true}
+		parser.SetEscapeToken(parser.DefaultEscapeToken, &d)
+
+		ast, err := parser.Parse(f, &d)
 		if err != nil {
 			panic(err)
 		} else {
diff --git a/frontend/dockerfile/parser/json_test.go b/frontend/dockerfile/parser/json_test.go
index a256f845..60d74d9c 100644
--- a/frontend/dockerfile/parser/json_test.go
+++ b/frontend/dockerfile/parser/json_test.go
@@ -28,7 +28,10 @@ var validJSONArraysOfStrings = map[string][]string{
 
 func TestJSONArraysOfStrings(t *testing.T) {
 	for json, expected := range validJSONArraysOfStrings {
-		if node, _, err := parseJSON(json); err != nil {
+		d := Directive{}
+		SetEscapeToken(DefaultEscapeToken, &d)
+
+		if node, _, err := parseJSON(json, &d); err != nil {
 			t.Fatalf("%q should be a valid JSON array of strings, but wasn't! (err: %q)", json, err)
 		} else {
 			i := 0
@@ -48,7 +51,10 @@ func TestJSONArraysOfStrings(t *testing.T) {
 		}
 	}
 	for _, json := range invalidJSONArraysOfStrings {
-		if _, _, err := parseJSON(json); err != errDockerfileNotStringArray {
+		d := Directive{}
+		SetEscapeToken(DefaultEscapeToken, &d)
+
+		if _, _, err := parseJSON(json, &d); err != errDockerfileNotStringArray {
 			t.Fatalf("%q should be an invalid JSON array of strings, but wasn't!", json)
 		}
 	}
diff --git a/frontend/dockerfile/parser/line_parsers.go b/frontend/dockerfile/parser/line_parsers.go
index 5f484e49..dec7a757 100644
--- a/frontend/dockerfile/parser/line_parsers.go
+++ b/frontend/dockerfile/parser/line_parsers.go
@@ -21,7 +21,7 @@ var (
 
 // ignore the current argument. This will still leave a command parsed, but
 // will not incorporate the arguments into the ast.
-func parseIgnore(rest string) (*Node, map[string]bool, error) {
+func parseIgnore(rest string, d *Directive) (*Node, map[string]bool, error) {
 	return &Node{}, nil, nil
 }
 
@@ -30,12 +30,12 @@ func parseIgnore(rest string) (*Node, map[string]bool, error) {
 //
 // ONBUILD RUN foo bar -> (onbuild (run foo bar))
 //
-func parseSubCommand(rest string) (*Node, map[string]bool, error) {
+func parseSubCommand(rest string, d *Directive) (*Node, map[string]bool, error) {
 	if rest == "" {
 		return nil, nil, nil
 	}
 
-	_, child, err := ParseLine(rest)
+	_, child, err := ParseLine(rest, d)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -46,7 +46,7 @@ func parseSubCommand(rest string) (*Node, map[string]bool, error) {
 // helper to parse words (i.e space delimited or quoted strings) in a statement.
 // The quotes are preserved as part of this function and they are stripped later
 // as part of processWords().
-func parseWords(rest string) []string {
+func parseWords(rest string, d *Directive) []string {
 	const (
 		inSpaces = iota // looking for start of a word
 		inWord
@@ -96,7 +96,7 @@ func parseWords(rest string) []string {
 				blankOK = true
 				phase = inQuote
 			}
-			if ch == tokenEscape {
+			if ch == d.EscapeToken {
 				if pos+chWidth == len(rest) {
 					continue // just skip an escape token at end of line
 				}
@@ -115,7 +115,7 @@ func parseWords(rest string) []string {
 				phase = inWord
 			}
 			// The escape token is special except for ' quotes - can't escape anything for '
-			if ch == tokenEscape && quote != '\'' {
+			if ch == d.EscapeToken && quote != '\'' {
 				if pos+chWidth == len(rest) {
 					phase = inWord
 					continue // just skip the escape token at end
@@ -133,14 +133,14 @@ func parseWords(rest string) []string {
 
 // parse environment like statements. Note that this does *not* handle
 // variable interpolation, which will be handled in the evaluator.
-func parseNameVal(rest string, key string) (*Node, map[string]bool, error) {
+func parseNameVal(rest string, key string, d *Directive) (*Node, map[string]bool, error) {
 	// This is kind of tricky because we need to support the old
 	// variant:   KEY name value
 	// as well as the new one:    KEY name=value ...
 	// The trigger to know which one is being used will be whether we hit
 	// a space or = first.  space ==> old, "=" ==> new
 
-	words := parseWords(rest)
+	words := parseWords(rest, d)
 	if len(words) == 0 {
 		return nil, nil, nil
 	}
@@ -187,12 +187,12 @@ func parseNameVal(rest string, key string) (*Node, map[string]bool, error) {
 	return rootnode, nil, nil
 }
 
-func parseEnv(rest string) (*Node, map[string]bool, error) {
-	return parseNameVal(rest, "ENV")
+func parseEnv(rest string, d *Directive) (*Node, map[string]bool, error) {
+	return parseNameVal(rest, "ENV", d)
 }
 
-func parseLabel(rest string) (*Node, map[string]bool, error) {
-	return parseNameVal(rest, "LABEL")
+func parseLabel(rest string, d *Directive) (*Node, map[string]bool, error) {
+	return parseNameVal(rest, "LABEL", d)
 }
 
 // parses a statement containing one or more keyword definition(s) and/or
@@ -203,8 +203,8 @@ func parseLabel(rest string) (*Node, map[string]bool, error) {
 // In addition, a keyword definition alone is of the form `keyword` like `name1`
 // above. And the assignments `name2=` and `name3=""` are equivalent and
 // assign an empty value to the respective keywords.
-func parseNameOrNameVal(rest string) (*Node, map[string]bool, error) {
-	words := parseWords(rest)
+func parseNameOrNameVal(rest string, d *Directive) (*Node, map[string]bool, error) {
+	words := parseWords(rest, d)
 	if len(words) == 0 {
 		return nil, nil, nil
 	}
@@ -229,7 +229,7 @@ func parseNameOrNameVal(rest string) (*Node, map[string]bool, error) {
 
 // parses a whitespace-delimited set of arguments. The result is effectively a
 // linked list of string arguments.
-func parseStringsWhitespaceDelimited(rest string) (*Node, map[string]bool, error) {
+func parseStringsWhitespaceDelimited(rest string, d *Directive) (*Node, map[string]bool, error) {
 	if rest == "" {
 		return nil, nil, nil
 	}
@@ -253,7 +253,7 @@ func parseStringsWhitespaceDelimited(rest string) (*Node, map[string]bool, error
 }
 
 // parsestring just wraps the string in quotes and returns a working node.
-func parseString(rest string) (*Node, map[string]bool, error) {
+func parseString(rest string, d *Directive) (*Node, map[string]bool, error) {
 	if rest == "" {
 		return nil, nil, nil
 	}
@@ -263,7 +263,7 @@ func parseString(rest string) (*Node, map[string]bool, error) {
 }
 
 // parseJSON converts JSON arrays to an AST.
-func parseJSON(rest string) (*Node, map[string]bool, error) {
+func parseJSON(rest string, d *Directive) (*Node, map[string]bool, error) {
 	rest = strings.TrimLeftFunc(rest, unicode.IsSpace)
 	if !strings.HasPrefix(rest, "[") {
 		return nil, nil, fmt.Errorf(`Error parsing "%s" as a JSON array`, rest)
@@ -296,12 +296,12 @@ func parseJSON(rest string) (*Node, map[string]bool, error) {
 // parseMaybeJSON determines if the argument appears to be a JSON array. If
 // so, passes to parseJSON; if not, quotes the result and returns a single
 // node.
-func parseMaybeJSON(rest string) (*Node, map[string]bool, error) {
+func parseMaybeJSON(rest string, d *Directive) (*Node, map[string]bool, error) {
 	if rest == "" {
 		return nil, nil, nil
 	}
 
-	node, attrs, err := parseJSON(rest)
+	node, attrs, err := parseJSON(rest, d)
 
 	if err == nil {
 		return node, attrs, nil
@@ -318,8 +318,8 @@ func parseMaybeJSON(rest string) (*Node, map[string]bool, error) {
 // parseMaybeJSONToList determines if the argument appears to be a JSON array. If
 // so, passes to parseJSON; if not, attempts to parse it as a whitespace
 // delimited string.
-func parseMaybeJSONToList(rest string) (*Node, map[string]bool, error) {
-	node, attrs, err := parseJSON(rest)
+func parseMaybeJSONToList(rest string, d *Directive) (*Node, map[string]bool, error) {
+	node, attrs, err := parseJSON(rest, d)
 
 	if err == nil {
 		return node, attrs, nil
@@ -328,11 +328,11 @@ func parseMaybeJSONToList(rest string) (*Node, map[string]bool, error) {
 		return nil, nil, err
 	}
 
-	return parseStringsWhitespaceDelimited(rest)
+	return parseStringsWhitespaceDelimited(rest, d)
 }
 
 // The HEALTHCHECK command is like parseMaybeJSON, but has an extra type argument.
-func parseHealthConfig(rest string) (*Node, map[string]bool, error) {
+func parseHealthConfig(rest string, d *Directive) (*Node, map[string]bool, error) {
 	// Find end of first argument
 	var sep int
 	for ; sep < len(rest); sep++ {
@@ -352,7 +352,7 @@ func parseHealthConfig(rest string) (*Node, map[string]bool, error) {
 	}
 
 	typ := rest[:sep]
-	cmd, attrs, err := parseMaybeJSON(rest[next:])
+	cmd, attrs, err := parseMaybeJSON(rest[next:], d)
 	if err != nil {
 		return nil, nil, err
 	}
diff --git a/frontend/dockerfile/parser/parser.go b/frontend/dockerfile/parser/parser.go
index f34a8f85..6fb84d92 100644
--- a/frontend/dockerfile/parser/parser.go
+++ b/frontend/dockerfile/parser/parser.go
@@ -36,26 +36,32 @@ type Node struct {
 	EndLine    int             // the line in the original dockerfile where the node ends
 }
 
-const defaultTokenEscape = "\\"
+// Directive is the structure used during a build run to hold the state of
+// parsing directives.
+type Directive struct {
+	EscapeToken           rune           // Current escape token
+	LineContinuationRegex *regexp.Regexp // Current line contination regex
+	LookingForDirectives  bool           // Whether we are currently looking for directives
+	EscapeSeen            bool           // Whether the escape directive has been seen
+}
 
 var (
-	dispatch              map[string]func(string) (*Node, map[string]bool, error)
-	tokenWhitespace       = regexp.MustCompile(`[\t\v\f\r ]+`)
-	tokenLineContinuation *regexp.Regexp
-	tokenEscape           = rune(defaultTokenEscape[0])
-	tokenEscapeCommand    = regexp.MustCompile(`^#[ \t]*escape[ \t]*=[ \t]*(?P<escapechar>.).*$`)
-	tokenComment          = regexp.MustCompile(`^#.*$`)
-	lookingForDirectives  bool
-	directiveEscapeSeen   bool
+	dispatch           map[string]func(string, *Directive) (*Node, map[string]bool, error)
+	tokenWhitespace    = regexp.MustCompile(`[\t\v\f\r ]+`)
+	tokenEscapeCommand = regexp.MustCompile(`^#[ \t]*escape[ \t]*=[ \t]*(?P<escapechar>.).*$`)
+	tokenComment       = regexp.MustCompile(`^#.*$`)
 )
 
-// setTokenEscape sets the default token for escaping characters in a Dockerfile.
-func setTokenEscape(s string) error {
+// DefaultEscapeToken is the default escape token
+const DefaultEscapeToken = "\\"
+
+// SetEscapeToken sets the default token for escaping characters in a Dockerfile.
+func SetEscapeToken(s string, d *Directive) error {
 	if s != "`" && s != "\\" {
 		return fmt.Errorf("invalid ESCAPE '%s'. Must be ` or \\", s)
 	}
-	tokenEscape = rune(s[0])
-	tokenLineContinuation = regexp.MustCompile(`\` + s + `[ \t]*$`)
+	d.EscapeToken = rune(s[0])
+	d.LineContinuationRegex = regexp.MustCompile(`\` + s + `[ \t]*$`)
 	return nil
 }
 
@@ -66,7 +72,7 @@ func init() {
 	// reformulating the arguments according to the rules in the parser
 	// functions. Errors are propagated up by Parse() and the resulting AST can
 	// be incorporated directly into the existing AST as a next.
-	dispatch = map[string]func(string) (*Node, map[string]bool, error){
+	dispatch = map[string]func(string, *Directive) (*Node, map[string]bool, error){
 		command.Add:         parseMaybeJSONToList,
 		command.Arg:         parseNameOrNameVal,
 		command.Cmd:         parseMaybeJSON,
@@ -89,36 +95,35 @@ func init() {
 }
 
 // ParseLine parse a line and return the remainder.
-func ParseLine(line string) (string, *Node, error) {
-
+func ParseLine(line string, d *Directive) (string, *Node, error) {
 	// Handle the parser directive '# escape=<char>. Parser directives must precede
 	// any builder instruction or other comments, and cannot be repeated.
-	if lookingForDirectives {
+	if d.LookingForDirectives {
 		tecMatch := tokenEscapeCommand.FindStringSubmatch(strings.ToLower(line))
 		if len(tecMatch) > 0 {
-			if directiveEscapeSeen == true {
+			if d.EscapeSeen == true {
 				return "", nil, fmt.Errorf("only one escape parser directive can be used")
 			}
 			for i, n := range tokenEscapeCommand.SubexpNames() {
 				if n == "escapechar" {
-					if err := setTokenEscape(tecMatch[i]); err != nil {
+					if err := SetEscapeToken(tecMatch[i], d); err != nil {
 						return "", nil, err
 					}
-					directiveEscapeSeen = true
+					d.EscapeSeen = true
 					return "", nil, nil
 				}
 			}
 		}
 	}
 
-	lookingForDirectives = false
+	d.LookingForDirectives = false
 
 	if line = stripComments(line); line == "" {
 		return "", nil, nil
 	}
 
-	if tokenLineContinuation.MatchString(line) {
-		line = tokenLineContinuation.ReplaceAllString(line, "")
+	if d.LineContinuationRegex.MatchString(line) {
+		line = d.LineContinuationRegex.ReplaceAllString(line, "")
 		return line, nil, nil
 	}
 
@@ -130,7 +135,7 @@ func ParseLine(line string) (string, *Node, error) {
 	node := &Node{}
 	node.Value = cmd
 
-	sexp, attrs, err := fullDispatch(cmd, args)
+	sexp, attrs, err := fullDispatch(cmd, args, d)
 	if err != nil {
 		return "", nil, err
 	}
@@ -145,10 +150,7 @@ func ParseLine(line string) (string, *Node, error) {
 
 // Parse is the main parse routine.
 // It handles an io.ReadWriteCloser and returns the root of the AST.
-func Parse(rwc io.Reader) (*Node, error) {
-	directiveEscapeSeen = false
-	lookingForDirectives = true
-	setTokenEscape(defaultTokenEscape) // Assume the default token for escape
+func Parse(rwc io.Reader, d *Directive) (*Node, error) {
 	currentLine := 0
 	root := &Node{}
 	root.StartLine = -1
@@ -163,7 +165,7 @@ func Parse(rwc io.Reader) (*Node, error) {
 		}
 		scannedLine := strings.TrimLeftFunc(string(scannedBytes), unicode.IsSpace)
 		currentLine++
-		line, child, err := ParseLine(scannedLine)
+		line, child, err := ParseLine(scannedLine, d)
 		if err != nil {
 			return nil, err
 		}
@@ -178,7 +180,7 @@ func Parse(rwc io.Reader) (*Node, error) {
 					continue
 				}
 
-				line, child, err = ParseLine(line + newline)
+				line, child, err = ParseLine(line+newline, d)
 				if err != nil {
 					return nil, err
 				}
@@ -188,7 +190,7 @@ func Parse(rwc io.Reader) (*Node, error) {
 				}
 			}
 			if child == nil && line != "" {
-				_, child, err = ParseLine(line)
+				_, child, err = ParseLine(line, d)
 				if err != nil {
 					return nil, err
 				}
diff --git a/frontend/dockerfile/parser/parser_test.go b/frontend/dockerfile/parser/parser_test.go
index 3c65a4a0..e7b0c07c 100644
--- a/frontend/dockerfile/parser/parser_test.go
+++ b/frontend/dockerfile/parser/parser_test.go
@@ -39,7 +39,9 @@ func TestTestNegative(t *testing.T) {
 			t.Fatalf("Dockerfile missing for %s: %v", dir, err)
 		}
 
-		_, err = Parse(df)
+		d := Directive{LookingForDirectives: true}
+		SetEscapeToken(DefaultEscapeToken, &d)
+		_, err = Parse(df, &d)
 		if err == nil {
 			t.Fatalf("No error parsing broken dockerfile for %s", dir)
 		}
@@ -59,7 +61,9 @@ func TestTestData(t *testing.T) {
 		}
 		defer df.Close()
 
-		ast, err := Parse(df)
+		d := Directive{LookingForDirectives: true}
+		SetEscapeToken(DefaultEscapeToken, &d)
+		ast, err := Parse(df, &d)
 		if err != nil {
 			t.Fatalf("Error parsing %s's dockerfile: %v", dir, err)
 		}
@@ -119,7 +123,9 @@ func TestParseWords(t *testing.T) {
 	}
 
 	for _, test := range tests {
-		words := parseWords(test["input"][0])
+		d := Directive{LookingForDirectives: true}
+		SetEscapeToken(DefaultEscapeToken, &d)
+		words := parseWords(test["input"][0], &d)
 		if len(words) != len(test["expect"]) {
 			t.Fatalf("length check failed. input: %v, expect: %q, output: %q", test["input"][0], test["expect"], words)
 		}
@@ -138,7 +144,9 @@ func TestLineInformation(t *testing.T) {
 	}
 	defer df.Close()
 
-	ast, err := Parse(df)
+	d := Directive{LookingForDirectives: true}
+	SetEscapeToken(DefaultEscapeToken, &d)
+	ast, err := Parse(df, &d)
 	if err != nil {
 		t.Fatalf("Error parsing dockerfile %s: %v", testFileLineInfo, err)
 	}
diff --git a/frontend/dockerfile/parser/utils.go b/frontend/dockerfile/parser/utils.go
index b21eb62a..cd7af75e 100644
--- a/frontend/dockerfile/parser/utils.go
+++ b/frontend/dockerfile/parser/utils.go
@@ -36,7 +36,7 @@ func (node *Node) Dump() string {
 
 // performs the dispatch based on the two primal strings, cmd and args. Please
 // look at the dispatch table in parser.go to see how these dispatchers work.
-func fullDispatch(cmd, args string) (*Node, map[string]bool, error) {
+func fullDispatch(cmd, args string, d *Directive) (*Node, map[string]bool, error) {
 	fn := dispatch[cmd]
 
 	// Ignore invalid Dockerfile instructions
@@ -44,7 +44,7 @@ func fullDispatch(cmd, args string) (*Node, map[string]bool, error) {
 		fn = parseIgnore
 	}
 
-	sexp, attrs, err := fn(args)
+	sexp, attrs, err := fn(args, d)
 	if err != nil {
 		return nil, nil, err
 	}