diff -r 020364d3e359 Include/opcode.h
--- a/Include/opcode.h	Sat Feb 25 16:24:59 2012 +0100
+++ b/Include/opcode.h	Sat Feb 25 18:20:43 2012 -0500
@@ -149,7 +149,7 @@
 
 #define SET_ADD         146
 #define MAP_ADD         147
-
+#define BUILD_LIST_FROM_ARG 148
 
 enum cmp_op {PyCmp_LT=Py_LT, PyCmp_LE=Py_LE, PyCmp_EQ=Py_EQ, PyCmp_NE=Py_NE, PyCmp_GT=Py_GT, PyCmp_GE=Py_GE,
 	     PyCmp_IN, PyCmp_NOT_IN, PyCmp_IS, PyCmp_IS_NOT, PyCmp_EXC_MATCH, PyCmp_BAD};
diff -r 020364d3e359 Lib/opcode.py
--- a/Lib/opcode.py	Sat Feb 25 16:24:59 2012 +0100
+++ b/Lib/opcode.py	Sat Feb 25 18:20:43 2012 -0500
@@ -188,5 +188,6 @@
 EXTENDED_ARG = 145
 def_op('SET_ADD', 146)
 def_op('MAP_ADD', 147)
+def_op('BUILD_LIST_FROM_ARG', 148)
 
 del def_op, name_op, jrel_op, jabs_op
diff -r 020364d3e359 Python/ceval.c
--- a/Python/ceval.c	Sat Feb 25 16:24:59 2012 +0100
+++ b/Python/ceval.c	Sat Feb 25 18:20:43 2012 -0500
@@ -2187,7 +2187,7 @@
             break;
 
         case BUILD_LIST:
-            x =  PyList_New(oparg);
+            x = PyList_New(oparg);
             if (x != NULL) {
                 for (; --oparg >= 0;) {
                     w = POP();
@@ -2198,6 +2198,19 @@
             }
             break;
 
+        case BUILD_LIST_FROM_ARG:
+            x = POP();
+            Py_ssize_t length = _PyObject_LengthHint(x, 0);
+            if (length != -1) {
+                w = PyList_New(length);
+                if (w != NULL) {
+                    Py_SIZE(w) = 0;
+                    PUSH(w);
+                    PUSH(x);
+                }
+            }
+            break;
+
         case BUILD_SET:
             x = PySet_New(NULL);
             if (x != NULL) {
diff -r 020364d3e359 Python/compile.c
--- a/Python/compile.c	Sat Feb 25 16:24:59 2012 +0100
+++ b/Python/compile.c	Sat Feb 25 18:20:43 2012 -0500
@@ -822,6 +822,8 @@
             return 1-oparg;
         case BUILD_MAP:
             return 1;
+        case BUILD_LIST_FROM_ARG:
+            return 1;
         case LOAD_ATTR:
             return 0;
         case COMPARE_OP:
@@ -2590,7 +2592,7 @@
 
 static int
 compiler_listcomp_generator(struct compiler *c, asdl_seq *generators,
-                            int gen_index, expr_ty elt)
+                            int gen_index, expr_ty elt, int single)
 {
     /* generate code for the iterator, then each of the ifs,
        and then write to the element */
@@ -2610,6 +2612,9 @@
 
     l = (comprehension_ty)asdl_seq_GET(generators, gen_index);
     VISIT(c, expr, l->iter);
+    if (single) {
+        ADDOP_I(c, BUILD_LIST_FROM_ARG, 0);
+    }
     ADDOP(c, GET_ITER);
     compiler_use_next_block(c, start);
     ADDOP_JREL(c, FOR_ITER, anchor);
@@ -2626,7 +2631,7 @@
     }
 
     if (++gen_index < asdl_seq_LEN(generators))
-        if (!compiler_listcomp_generator(c, generators, gen_index, elt))
+        if (!compiler_listcomp_generator(c, generators, gen_index, elt, 0))
         return 0;
 
     /* only append after the last for generator */
@@ -2646,10 +2651,15 @@
 static int
 compiler_listcomp(struct compiler *c, expr_ty e)
 {
+    int single;
     assert(e->kind == ListComp_kind);
-    ADDOP_I(c, BUILD_LIST, 0);
+    single = (asdl_seq_LEN(e->v.ListComp.generators) == 1 &&
+        !asdl_seq_LEN(((comprehension_ty)asdl_seq_GET(e->v.ListComp.generators, 0))->ifs));
+    if (!single) {
+        ADDOP_I(c, BUILD_LIST, 0);
+    }
     return compiler_listcomp_generator(c, e->v.ListComp.generators, 0,
-                                       e->v.ListComp.elt);
+                                       e->v.ListComp.elt, single);
 }
 
 /* Dict and set comprehensions and generator expressions work by creating a