diff --git a/js/src/frontend/ParseNode-inl.h b/js/src/frontend/ParseNode-inl.h
index 4de49569f3b..e6c43c019b6 100644
--- a/js/src/frontend/ParseNode-inl.h
+++ b/js/src/frontend/ParseNode-inl.h
@@ -64,6 +64,131 @@ ParseNode::isConstant()
     }
 }
 
+#ifdef DEBUG
+inline void
+IndentNewLine(int indent)
+{
+    fputc('\n', stderr);
+    for (int i = 0; i < indent; ++i)
+        fputc(' ', stderr);
+}
+
+inline void
+ParseNode::dump(int indent)
+{
+    switch (pn_arity) {
+      case PN_NULLARY:
+        ((NullaryNode *) this)->dump();
+        break;
+      case PN_UNARY:
+        ((UnaryNode *) this)->dump(indent);
+        break;
+      case PN_BINARY:
+        ((BinaryNode *) this)->dump(indent);
+        break;
+      case PN_TERNARY:
+        ((TernaryNode *) this)->dump(indent);
+        break;
+      case PN_FUNC:
+        ((FunctionNode *) this)->dump(indent);
+        break;
+      case PN_LIST:
+        ((ListNode *) this)->dump(indent);
+        break;
+      case PN_NAME:
+        ((NameNode *) this)->dump(indent);
+        break;
+      default:
+        fprintf(stderr, "?");
+        break;
+    }
+}
+
+inline void
+NullaryNode::dump()
+{
+    fprintf(stderr, "(%s)", js_CodeName[getOp()]);
+}
+
+inline void
+UnaryNode::dump(int indent)
+{
+    const char *name = js_CodeName[getOp()];
+    fprintf(stderr, "(%s ", name);
+    indent += strlen(name) + 2;
+    DumpParseTree(pn_kid, indent);
+    fprintf(stderr, ")");
+}
+
+inline void
+BinaryNode::dump(int indent)
+{
+    const char *name = js_CodeName[getOp()];
+    fprintf(stderr, "(%s ", name);
+    indent += strlen(name) + 2;
+    DumpParseTree(pn_left, indent);
+    IndentNewLine(indent);
+    DumpParseTree(pn_right, indent);
+    fprintf(stderr, ")");
+}
+
+inline void
+TernaryNode::dump(int indent)
+{
+    const char *name = js_CodeName[getOp()];
+    fprintf(stderr, "(%s ", name);
+    indent += strlen(name) + 2;
+    DumpParseTree(pn_kid1, indent);
+    IndentNewLine(indent);
+    DumpParseTree(pn_kid2, indent);
+    IndentNewLine(indent);
+    DumpParseTree(pn_kid3, indent);
+    fprintf(stderr, ")");
+}
+
+inline void
+FunctionNode::dump(int indent)
+{
+    const char *name = js_CodeName[getOp()];
+    fprintf(stderr, "(%s ", name);
+    indent += strlen(name) + 2;
+    DumpParseTree(pn_body, indent);
+    fprintf(stderr, ")");
+}
+
+inline void
+ListNode::dump(int indent)
+{
+    const char *name = js_CodeName[getOp()];
+    fprintf(stderr, "(%s ", name);
+    if (pn_head != NULL) {
+        indent += strlen(name) + 2;
+        DumpParseTree(pn_head, indent);
+        ParseNode *pn = pn_head->pn_next;
+        while (pn != NULL) {
+            IndentNewLine(indent);
+            DumpParseTree(pn, indent);
+            pn = pn->pn_next;
+        }
+    }
+    fprintf(stderr, ")");
+}
+
+inline void
+NameNode::dump(int indent)
+{
+    const char *name = js_CodeName[getOp()];
+    if (isUsed())
+        fprintf(stderr, "(%s)", name);
+    else {
+        fprintf(stderr, "(%s ", name);
+        indent += strlen(name) + 2;
+        DumpParseTree(expr(), indent);
+        fprintf(stderr, ")");
+    }
+}
+#endif
+
 inline void
 NameNode::initCommon(TreeContext *tc)
 {
diff --git a/js/src/frontend/ParseNode.cpp b/js/src/frontend/ParseNode.cpp
index 8c4132dd4c0..c3534a21bee 100644
--- a/js/src/frontend/ParseNode.cpp
+++ b/js/src/frontend/ParseNode.cpp
@@ -660,3 +660,14 @@ js::CloneLeftHandSide(ParseNode *opn, TreeContext *tc)
     }
     return pn;
 }
+
+#ifdef DEBUG
+void
+js::DumpParseTree(ParseNode *pn, int indent)
+{
+    if (pn == NULL) 
+        fprintf(stderr, "()");
+    else
+        pn->dump(indent);
+}
+#endif
diff --git a/js/src/frontend/ParseNode.h b/js/src/frontend/ParseNode.h
index 96c2cb90357..ce5d219d4ea 100644
--- a/js/src/frontend/ParseNode.h
+++ b/js/src/frontend/ParseNode.h
@@ -929,12 +929,20 @@ struct ParseNode {
 #endif
     inline ConditionalExpression &asConditionalExpression();
     inline PropertyAccess &asPropertyAccess();
+
+#ifdef DEBUG
+    inline void dump(int indent);
+#endif
 };
 
 struct NullaryNode : public ParseNode {
     static inline NullaryNode *create(ParseNodeKind kind, TreeContext *tc) {
         return (NullaryNode *)ParseNode::create(kind, PN_NULLARY, tc);
     }
+
+#ifdef DEBUG
+    inline void dump();
+#endif
 };
 
 struct UnaryNode : public ParseNode {
@@ -947,6 +955,10 @@ struct UnaryNode : public ParseNode {
     static inline UnaryNode *create(ParseNodeKind kind, TreeContext *tc) {
         return (UnaryNode *)ParseNode::create(kind, PN_UNARY, tc);
     }
+
+#ifdef DEBUG
+    inline void dump(int indent);
+#endif
 };
 
 struct BinaryNode : public ParseNode {
@@ -967,6 +979,10 @@ struct BinaryNode : public ParseNode {
     static inline BinaryNode *create(ParseNodeKind kind, TreeContext *tc) {
         return (BinaryNode *)ParseNode::create(kind, PN_BINARY, tc);
     }
+
+#ifdef DEBUG
+    inline void dump(int indent);
+#endif
 };
 
 struct TernaryNode : public ParseNode {
@@ -983,24 +999,40 @@ struct TernaryNode : public ParseNode {
     static inline TernaryNode *create(ParseNodeKind kind, TreeContext *tc) {
         return (TernaryNode *)ParseNode::create(kind, PN_TERNARY, tc);
     }
+
+#ifdef DEBUG
+    inline void dump(int indent);
+#endif
 };
 
 struct ListNode : public ParseNode {
     static inline ListNode *create(ParseNodeKind kind, TreeContext *tc) {
         return (ListNode *)ParseNode::create(kind, PN_LIST, tc);
     }
+
+#ifdef DEBUG
+    inline void dump(int indent);
+#endif
 };
 
 struct FunctionNode : public ParseNode {
     static inline FunctionNode *create(ParseNodeKind kind, TreeContext *tc) {
         return (FunctionNode *)ParseNode::create(kind, PN_FUNC, tc);
     }
+
+#ifdef DEBUG
+    inline void dump(int indent);
+#endif
 };
 
 struct NameNode : public ParseNode {
     static NameNode *create(ParseNodeKind kind, JSAtom *atom, TreeContext *tc);
 
     inline void initCommon(TreeContext *tc);
+
+#ifdef DEBUG
+    inline void dump(int indent);
+#endif
 };
 
 struct NameSetNode : public ParseNode {
@@ -1254,6 +1286,10 @@ class PropertyByValue : public ParseNode {
 ParseNode *
 CloneLeftHandSide(ParseNode *opn, TreeContext *tc);
 
+#ifdef DEBUG
+void DumpParseTree(ParseNode *pn, int indent = 0);
+#endif
+
 /*
  * js::Definition is a degenerate subtype of the PN_FUNC and PN_NAME variants
  * of js::ParseNode, allocated only for function, var, const, and let
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index a21cf9db94e..b0feda55fd6 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -3704,8 +3704,12 @@ Parse(JSContext *cx, uintN argc, jsval *vp)
     js::Parser parser(cx);
     parser.init(JS_GetStringCharsZ(cx, scriptContents), JS_GetStringLength(scriptContents),
                 "<string>", 0, cx->findVersion());
-    if (!parser.parse(NULL))
+    ParseNode *pn = parser.parse(NULL);
+    if (!pn)
         return JS_FALSE;
+#ifdef DEBUG
+    DumpParseTree(pn);
+#endif
     JS_SET_RVAL(cx, vp, JSVAL_VOID);
     return JS_TRUE;
 }