diff --git a/source/blender/blenkernel/intern/constraint.cc b/source/blender/blenkernel/intern/constraint.cc
index e2d4c06a5ae..f1d45e5192e 100644
--- a/source/blender/blenkernel/intern/constraint.cc
+++ b/source/blender/blenkernel/intern/constraint.cc
@@ -2915,6 +2915,11 @@ static void actcon_evaluate(bConstraint *con, bConstraintOb *cob, ListBase *targ
 
   if (VALID_CONS_TARGET(ct) || data->flag & ACTCON_USE_EVAL_TIME) {
     switch (data->mix_mode) {
+      /* Replace the input transformation. */
+      case ACTCON_MIX_REPLACE:
+        copy_m4_m4(cob->matrix, ct->matrix);
+        break;
+
       /* Simple matrix multiplication. */
       case ACTCON_MIX_BEFORE_FULL:
         mul_m4_m4m4(cob->matrix, ct->matrix, cob->matrix);
diff --git a/source/blender/makesdna/DNA_constraint_types.h b/source/blender/makesdna/DNA_constraint_types.h
index 0bb44d77d97..86a7487d0a3 100644
--- a/source/blender/makesdna/DNA_constraint_types.h
+++ b/source/blender/makesdna/DNA_constraint_types.h
@@ -842,6 +842,8 @@ typedef enum eActionConstraint_Flags {
 
 /** #bActionConstraint.mix_mode */
 typedef enum eActionConstraint_MixMode {
+  /* Replace the input transformation. */
+  ACTCON_MIX_REPLACE = 6,
   /* Multiply the action transformation on the right. */
   ACTCON_MIX_AFTER_FULL = 0,
   /* Multiply the action transformation on the left. */
diff --git a/source/blender/makesrna/intern/rna_constraint.cc b/source/blender/makesrna/intern/rna_constraint.cc
index 663bb2b1917..4fc5ab608c8 100644
--- a/source/blender/makesrna/intern/rna_constraint.cc
+++ b/source/blender/makesrna/intern/rna_constraint.cc
@@ -1848,6 +1848,12 @@ static void rna_def_constraint_action(BlenderRNA *brna)
   };
 
   static const EnumPropertyItem mix_mode_items[] = {
+      {ACTCON_MIX_REPLACE,
+       "REPLACE",
+       0,
+       "Replace",
+       "Replace the original transformation with the action channels"},
+      RNA_ENUM_ITEM_SEPR,
       {ACTCON_MIX_BEFORE_FULL,
        "BEFORE_FULL",
        0,
diff --git a/tests/python/bl_constraints.py b/tests/python/bl_constraints.py
index 431f00fe018..4e76d46f422 100644
--- a/tests/python/bl_constraints.py
+++ b/tests/python/bl_constraints.py
@@ -460,6 +460,47 @@ class ActionConstraintTest(AbstractConstraintTests):
             con.action_slot,
             "Assigning an Action with a virgin slot should automatically select that slot")
 
+    def test_mix_modes(self):
+        owner = bpy.context.scene.objects["Action.owner"]
+        target = bpy.context.scene.objects["Action.target"]
+
+        action = bpy.data.actions.new("Slotted")
+        slot = action.slots.new('OBJECT', "Slot")
+        layer = action.layers.new(name="Layer")
+        strip = layer.strips.new(type='KEYFRAME')
+        strip.key_insert(slot, "location", 0, 2.0, 0.0)
+        strip.key_insert(slot, "location", 0, 7.0, 10.0)
+
+        con = owner.constraints["Action"]
+        con.action = action
+        con.action_slot = slot
+        con.transform_channel = 'LOCATION_X'
+        con.min = -1.0
+        con.max = 1.0
+        con.frame_start = 0
+        con.frame_end = 10
+
+        # Set the constrained object's location to something other than [0,0,0],
+        # so we can verify that it's actually replaced/mixed as appropriate to
+        # the mix mode.
+        owner.location = (2.0, 3.0, 4.0)
+
+        con.mix_mode = 'REPLACE'
+        self.matrix_test("Action.owner", Matrix((
+            (1.0, 0.0, 0.0, 4.5),
+            (0.0, 1.0, 0.0, 0.0),
+            (0.0, 0.0, 1.0, 0.0),
+            (0.0, 0.0, 0.0, 1.0)
+        )))
+
+        con.mix_mode = 'BEFORE_SPLIT'
+        self.matrix_test("Action.owner", Matrix((
+            (1.0, 0.0, 0.0, 6.5),
+            (0.0, 1.0, 0.0, 3.0),
+            (0.0, 0.0, 1.0, 4.0),
+            (0.0, 0.0, 0.0, 1.0)
+        )))
+
 
 def main():
     global args