diff --git a/src/cmd/compile/internal/ir/copy.go b/src/cmd/compile/internal/ir/copy.go
index 86e78cfc33..7f5d313513 100644
--- a/src/cmd/compile/internal/ir/copy.go
+++ b/src/cmd/compile/internal/ir/copy.go
@@ -70,33 +70,12 @@ func copyList(x Nodes) Nodes {
 	return AsNodes(c)
 }
 
-// A Node can implement DeepCopyNode to provide a custom implementation
-// of DeepCopy. If the compiler only needs access to a Node's structure during
-// DeepCopy, then a Node can implement DeepCopyNode instead of providing
-// fine-grained mutable access with Left, SetLeft, Right, SetRight, and so on.
-type DeepCopyNode interface {
-	Node
-	DeepCopy(pos src.XPos) Node
-}
-
 // DeepCopy returns a “deep” copy of n, with its entire structure copied
 // (except for shared nodes like ONAME, ONONAME, OLITERAL, and OTYPE).
 // If pos.IsKnown(), it sets the source position of newly allocated Nodes to pos.
-//
-// The default implementation is to traverse the Node graph, making
-// a shallow copy of each node and then updating each field to point
-// at shallow copies of children, recursively, using Left, SetLeft, and so on.
-//
-// If a Node wishes to provide an alternate implementation, it can
-// implement a DeepCopy method: see the DeepCopyNode interface.
-//
-// TODO(rsc): Once Nodes implement EditChildren, remove the DeepCopyNode interface.
 func DeepCopy(pos src.XPos, n Node) Node {
 	var edit func(Node) Node
 	edit = func(x Node) Node {
-		if x, ok := x.(DeepCopyNode); ok {
-			return x.DeepCopy(pos)
-		}
 		switch x.Op() {
 		case OPACK, ONAME, ONONAME, OLITERAL, ONIL, OTYPE:
 			return x
diff --git a/src/cmd/compile/internal/ir/expr.go b/src/cmd/compile/internal/ir/expr.go
index 312faa8436..cfdb86f221 100644
--- a/src/cmd/compile/internal/ir/expr.go
+++ b/src/cmd/compile/internal/ir/expr.go
@@ -1163,17 +1163,6 @@ func (n *StarExpr) SetOTYPE(t *types.Type) {
 	t.SetNod(n)
 }
 
-func (n *StarExpr) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	c := SepCopy(n).(*StarExpr)
-	c.pos = n.posOr(pos)
-	c.X = DeepCopy(pos, n.X)
-	return c
-}
-
 // A TypeAssertionExpr is a selector expression X.(Type).
 // Before type-checking, the type is Ntype.
 type TypeAssertExpr struct {
diff --git a/src/cmd/compile/internal/ir/type.go b/src/cmd/compile/internal/ir/type.go
index d69dc3fd2a..9f82c9faa2 100644
--- a/src/cmd/compile/internal/ir/type.go
+++ b/src/cmd/compile/internal/ir/type.go
@@ -88,14 +88,6 @@ func (n *ChanType) SetOTYPE(t *types.Type) {
 	n.Elem = nil
 }
 
-func (n *ChanType) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	return NewChanType(n.posOr(pos), DeepCopy(pos, n.Elem), n.Dir)
-}
-
 // A MapType represents a map[Key]Value type syntax.
 type MapType struct {
 	miniType
@@ -129,14 +121,6 @@ func (n *MapType) SetOTYPE(t *types.Type) {
 	n.Elem = nil
 }
 
-func (n *MapType) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	return NewMapType(n.posOr(pos), DeepCopy(pos, n.Key), DeepCopy(pos, n.Elem))
-}
-
 // A StructType represents a struct { ... } type syntax.
 type StructType struct {
 	miniType
@@ -171,14 +155,6 @@ func (n *StructType) SetOTYPE(t *types.Type) {
 	n.Fields = nil
 }
 
-func (n *StructType) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	return NewStructType(n.posOr(pos), deepCopyFields(pos, n.Fields))
-}
-
 func deepCopyFields(pos src.XPos, fields []*Field) []*Field {
 	var out []*Field
 	for _, f := range fields {
@@ -221,14 +197,6 @@ func (n *InterfaceType) SetOTYPE(t *types.Type) {
 	n.Methods = nil
 }
 
-func (n *InterfaceType) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	return NewInterfaceType(n.posOr(pos), deepCopyFields(pos, n.Methods))
-}
-
 // A FuncType represents a func(Args) Results type syntax.
 type FuncType struct {
 	miniType
@@ -275,17 +243,6 @@ func (n *FuncType) SetOTYPE(t *types.Type) {
 	n.Results = nil
 }
 
-func (n *FuncType) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	return NewFuncType(n.posOr(pos),
-		n.Recv.deepCopy(pos),
-		deepCopyFields(pos, n.Params),
-		deepCopyFields(pos, n.Results))
-}
-
 // A Field is a declared struct field, interface method, or function argument.
 // It is not a Node.
 type Field struct {
@@ -424,14 +381,6 @@ func (n *SliceType) SetOTYPE(t *types.Type) {
 	n.Elem = nil
 }
 
-func (n *SliceType) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	return NewSliceType(n.posOr(pos), DeepCopy(pos, n.Elem))
-}
-
 // An ArrayType represents a [Len]Elem type syntax.
 // If Len is nil, the type is a [...]Elem in an array literal.
 type ArrayType struct {
@@ -461,14 +410,6 @@ func (n *ArrayType) editChildren(edit func(Node) Node) {
 	n.Elem = maybeEdit(n.Elem, edit)
 }
 
-func (n *ArrayType) DeepCopy(pos src.XPos) Node {
-	if n.op == OTYPE {
-		// Can't change types and no node references left.
-		return n
-	}
-	return NewArrayType(n.posOr(pos), DeepCopy(pos, n.Len), DeepCopy(pos, n.Elem))
-}
-
 func (n *ArrayType) SetOTYPE(t *types.Type) {
 	n.setOTYPE(t, n)
 	n.Len = nil