diff --git a/Include/dictobject.h b/Include/dictobject.h
index fec6295..c5378cf 100644
--- a/Include/dictobject.h
+++ b/Include/dictobject.h
@@ -110,6 +110,7 @@
 PyAPI_FUNC(PyObject *) PyDict_Copy(PyObject *mp);
 PyAPI_FUNC(int) PyDict_Contains(PyObject *mp, PyObject *key);
 PyAPI_FUNC(int) _PyDict_Contains(PyObject *mp, PyObject *key, long hash);
+PyAPI_FUNC(PyObject *) _PyDict_NewPresized(Py_ssize_t minused);
 
 /* PyDict_Update(mp, other) is equivalent to PyDict_Merge(mp, other, 1). */
 PyAPI_FUNC(int) PyDict_Update(PyObject *mp, PyObject *other);
diff --git a/Lib/opcode.py b/Lib/opcode.py
index c3457d0..cee5057 100644
--- a/Lib/opcode.py
+++ b/Lib/opcode.py
@@ -139,7 +139,7 @@
 name_op('LOAD_NAME', 101)       # Index in name list
 def_op('BUILD_TUPLE', 102)      # Number of tuple items
 def_op('BUILD_LIST', 103)       # Number of list items
-def_op('BUILD_MAP', 104)        # Always zero for now
+def_op('BUILD_MAP', 104)        # Number of dict entries (upto 255)
 name_op('LOAD_ATTR', 105)       # Index in name list
 def_op('COMPARE_OP', 106)       # Comparison operator
 hascompare.append(106)
diff --git a/Misc/NEWS b/Misc/NEWS
index 1599ade..40e9e6a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,10 @@
 Core and builtins
 -----------------
 
+- Compiler now generates simpler and faster code for dictionary literals.
+  The oparg for BUILD_MAP now indicates an estimated dictionary size.
+  There is a new opcode, STORE_MAP, for adding entries to the dictionary.
+
 - Issue #1638: %zd configure test fails on Linux
 
 - Issue #1620: New property decorator syntax was modifying the decorator
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index bfb093b..365aac6 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -549,6 +549,23 @@
 	return 0;
 }
 
+/* Create a new dictionary pre-sized to hold an estimated number of elements.
+   Underestimates are okay because the dictionary will resize as necessary.
+   Overestimates just mean the dictionary will be more sparse than usual.
+*/
+
+PyObject *
+_PyDict_NewPresized(Py_ssize_t minused)
+{
+	PyObject *op = PyDict_New();
+
+	if (minused>5 && op != NULL && dictresize((PyDictObject *)op, minused) == -1) {
+		Py_DECREF(op);
+		return NULL;
+	}
+	return op;
+}
+
 /* Note that, for historical reasons, PyDict_GetItem() suppresses all errors
  * that may occur (originally dicts supported only string keys, and exceptions
  * weren't possible).  So, while the original intent was that a NULL return
diff --git a/Python/ceval.c b/Python/ceval.c
index 1af998d..b6501b3 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1997,7 +1997,7 @@
 			break;
 
 		case BUILD_MAP:
-			x = PyDict_New();
+			x = _PyDict_NewPresized((Py_ssize_t)oparg);
 			PUSH(x);
 			if (x != NULL) continue;
 			break;
diff --git a/Python/compile.c b/Python/compile.c
index 3b0c53f..36ad8a4 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -2922,11 +2922,9 @@
 	case IfExp_kind:
 		return compiler_ifexp(c, e);
 	case Dict_kind:
-		/* XXX get rid of arg? */
-		ADDOP_I(c, BUILD_MAP, 0);
 		n = asdl_seq_LEN(e->v.Dict.values);
-		/* We must arrange things just right for STORE_SUBSCR.
-		   It wants the stack to look like (value) (dict) (key) */
+		ADDOP_I(c, BUILD_MAP, (n>255 ? 255 : n));
+		n = asdl_seq_LEN(e->v.Dict.values);
 		for (i = 0; i < n; i++) {
 			VISIT(c, expr, 
 				(expr_ty)asdl_seq_GET(e->v.Dict.values, i));