diff --git a/README.markdown b/README.markdown
index ccbc26f1..646f262f 100644
--- a/README.markdown
+++ b/README.markdown
@@ -37,6 +37,7 @@ Slic3r current key features are:
 * multiple solid layers near horizontal external surfaces;
 * ability to scale, rotate and duplicate input object;
 * customizable initial and final GCODE;
+* support material;
 * use different speed for bottom layer and perimeters.
 
 Experimental features include:
@@ -150,6 +151,7 @@ The author is Alessandro Ranellucci (me).
         --end-gcode         Load final gcode from the supplied file. This will overwrite 
                             the default commands (turn off temperature [M104 S0],
                             home X axis [G28 X], disable motors [M84]).
+        --support-material  Generate support material for overhangs
       
       Retraction options:
         --retract-length    Length of retraction in mm when pausing extrusion 
diff --git a/lib/Slic3r.pm b/lib/Slic3r.pm
index ad09842f..973537c7 100644
--- a/lib/Slic3r.pm
+++ b/lib/Slic3r.pm
@@ -95,6 +95,7 @@ our $fill_pattern       = 'rectilinear';
 our $solid_fill_pattern = 'rectilinear';
 our $fill_density       = 0.4;  # 1 = 100%
 our $fill_angle         = 45;
+our $support_material   = 0;
 our $start_gcode = "G28 ; home all axes";
 our $end_gcode = <<"END";
 M104 S0 ; turn off temperature
diff --git a/lib/Slic3r/Config.pm b/lib/Slic3r/Config.pm
index b46bcd34..6e8579a9 100644
--- a/lib/Slic3r/Config.pm
+++ b/lib/Slic3r/Config.pm
@@ -215,6 +215,11 @@ our $Options = {
         cli     => 'fill-angle=i',
         type    => 'i',
     },
+    'support_material' => {
+        label   => 'Generate support material',
+        cli     => 'support-material',
+        type    => 'bool',
+    },
     'start_gcode' => {
         label   => 'Start GCODE',
         cli     => 'start-gcode=s',
diff --git a/lib/Slic3r/Extruder.pm b/lib/Slic3r/Extruder.pm
index 25381011..59efadf9 100644
--- a/lib/Slic3r/Extruder.pm
+++ b/lib/Slic3r/Extruder.pm
@@ -149,7 +149,7 @@ sub extrude_path {
     
     # extrude arc or line
     $self->print_feed_rate(
-        $path->role =~ /^(perimeter|skirt)$/o   ? $self->perimeter_speed
+        $path->role =~ /^(perimeter|skirt|support-material)$/o ? $self->perimeter_speed
             : $path->role eq 'small-perimeter'  ? $self->small_perimeter_speed
             : $path->role eq 'fill'             ? $self->infill_speed
             : $path->role eq 'solid-fill'       ? $self->solid_infill_speed
diff --git a/lib/Slic3r/ExtrusionLoop.pm b/lib/Slic3r/ExtrusionLoop.pm
index ed91651b..e0095474 100644
--- a/lib/Slic3r/ExtrusionLoop.pm
+++ b/lib/Slic3r/ExtrusionLoop.pm
@@ -44,4 +44,9 @@ sub split_at {
     );
 }
 
+sub split_at_first_point {
+    my $self = shift;
+    return $self->split_at($self->polygon->[0]);
+}
+
 1;
diff --git a/lib/Slic3r/ExtrusionPath.pm b/lib/Slic3r/ExtrusionPath.pm
index 4f8a5b4c..fca81338 100644
--- a/lib/Slic3r/ExtrusionPath.pm
+++ b/lib/Slic3r/ExtrusionPath.pm
@@ -17,7 +17,7 @@ has 'depth_layers' => (is => 'ro', default => sub {1});
 
 has 'flow_spacing' => (is => 'rw');
 
-# perimeter/fill/solid-fill/bridge/skirt
+# perimeter/fill/solid-fill/bridge/skirt/support-material
 has 'role'         => (is => 'rw', required => 1);
 
 sub BUILD {
@@ -45,6 +45,22 @@ sub clip_end {
     }
 }
 
+sub clip_with_expolygon {
+    my $self = shift;
+    my ($expolygon) = @_;
+    
+    my @paths = ();
+    foreach my $polyline ($self->polyline->clip_with_expolygon($expolygon)) {
+        push @paths, (ref $self)->new(
+            polyline        => $polyline,
+            depth_layers    => $self->depth_layers,
+            flow_spacing    => $self->flow_spacing,
+            role            => $self->role,
+        );
+    }
+    return @paths;
+}
+
 sub points {
     my $self = shift;
     return $self->polyline;
diff --git a/lib/Slic3r/Fill.pm b/lib/Slic3r/Fill.pm
index 63c3174a..e03a5053 100644
--- a/lib/Slic3r/Fill.pm
+++ b/lib/Slic3r/Fill.pm
@@ -34,17 +34,16 @@ sub BUILD {
     my $self = shift;
     $self->fillers->{$_} ||= $FillTypes{$_}->new(print => $self->print)
         for ('rectilinear', $Slic3r::fill_pattern, $Slic3r::solid_fill_pattern);
+    
+    my $max_print_dimension = $self->print->max_length * sqrt(2);
+    $_->max_print_dimension($max_print_dimension) for values %{$self->fillers};
 }
 
 sub make_fill {
     my $self = shift;
     my ($layer) = @_;
     
-    my $max_print_dimension = $self->print->max_length * sqrt(2);
-    for (values %{$self->fillers}) {
-        $_->layer($layer);
-        $_->max_print_dimension($max_print_dimension);
-    }
+    $_->layer($layer) for values %{$self->fillers};
     
     printf "Filling layer %d:\n", $layer->id;
     
diff --git a/lib/Slic3r/Fill/Base.pm b/lib/Slic3r/Fill/Base.pm
index 5dc47d8f..63e3cedd 100644
--- a/lib/Slic3r/Fill/Base.pm
+++ b/lib/Slic3r/Fill/Base.pm
@@ -18,13 +18,15 @@ sub infill_direction {
     $rotate[1] = [ $self->max_print_dimension * sqrt(2) / 2, $self->max_print_dimension * sqrt(2) / 2 ];
     @shift = @{$rotate[1]};
     
-    # alternate fill direction
-    if (($self->layer->id / $surface->depth_layers) % 2) {
-        $rotate[0] = Slic3r::Geometry::deg2rad($Slic3r::fill_angle) + PI/2;
+    if ($self->layer) {
+        # alternate fill direction
+        if (($self->layer->id / $surface->depth_layers) % 2) {
+            $rotate[0] = Slic3r::Geometry::deg2rad($Slic3r::fill_angle) + PI/2;
+        }
     }
-    
+        
     # use bridge angle
-    if ($surface->surface_type eq 'bottom' && $self->layer->id > 0 && defined $surface->bridge_angle) {
+    if (defined $surface->bridge_angle) {
         Slic3r::debugf "Filling bridge with angle %d\n", $surface->bridge_angle;
         $rotate[0] = Slic3r::Geometry::deg2rad($surface->bridge_angle);
     }
diff --git a/lib/Slic3r/Layer.pm b/lib/Slic3r/Layer.pm
index 9b6fb560..7adce89a 100644
--- a/lib/Slic3r/Layer.pm
+++ b/lib/Slic3r/Layer.pm
@@ -66,10 +66,16 @@ has 'skirts' => (
     default => sub { [] },
 );
 
+# ordered collection of extrusion paths to fill surfaces for support material
+has 'support_fills' => (
+    is      => 'rw',
+    #isa     => 'Slic3r::ExtrusionPath::Collection',
+);
+
 # ordered collection of extrusion paths to fill surfaces
 has 'fills' => (
     is      => 'rw',
-    #isa     => 'ArrayRef[Slic3r::ExtrusionPath]',
+    #isa     => 'ArrayRef[Slic3r::ExtrusionPath::Collection]',
     default => sub { [] },
 );
 
diff --git a/lib/Slic3r/Print.pm b/lib/Slic3r/Print.pm
index 8042b752..b1f8f228 100644
--- a/lib/Slic3r/Print.pm
+++ b/lib/Slic3r/Print.pm
@@ -342,6 +342,7 @@ sub extrude_skirt {
     my @points = (
         (map @$_, map @{$_->expolygon}, map @{$_->slices}, @layers),
         (map @$_, map @{$_->thin_walls}, @layers),
+        (map @{$_->polyline}, map @{$_->support_fills->paths}, grep $_->support_fills, @layers),
     );
     return if !@points;
     
@@ -451,6 +452,74 @@ sub infill_every_layers {
     }
 }
 
+sub generate_support_material {
+    my $self = shift;
+    
+    # generate paths for the pattern that we're going to use
+    my $support_pattern = [];
+    {
+        # get all surfaces needing support material
+        my @surfaces = grep $_->surface_type eq 'bottom' && !defined $_->bridge_angle,
+            map @{$_->slices}, grep $_->id > 0, @{$self->layers} or return;
+        
+        my @support_material_areas = @{union_ex([ map $_->p, @surfaces ])};
+        
+        for (1..$Slic3r::perimeters+1) {
+            foreach my $expolygon (@support_material_areas) {
+                push @$support_pattern,
+                    map Slic3r::ExtrusionLoop->new(
+                        polygon => $_,
+                        role    => 'support-material',
+                    )->split_at_first_point, @$expolygon;
+            }
+            @support_material_areas = map $_->offset_ex(- scale $Slic3r::flow_spacing),
+                @support_material_areas;
+        }
+        
+        my $fill = Slic3r::Fill->new(print => $self);
+        foreach my $expolygon (@support_material_areas) {
+            my @paths = $fill->fillers->{rectilinear}->fill_surface(
+                Slic3r::Surface->new(
+                    expolygon       => $expolygon,
+                    bridge_angle    => $Slic3r::fill_angle + 45,
+                ),
+                density         => 0.15,
+                flow_spacing    => $Slic3r::flow_spacing,
+            );
+            my $params = shift @paths;
+            
+            push @$support_pattern,
+                map Slic3r::ExtrusionPath->new(
+                    polyline        => Slic3r::Polyline->new(@$_),
+                    role            => 'support-material',
+                    depth_layers    => 1,
+                    flow_spacing    => $params->{flow_spacing},
+                ), @paths;
+        }
+    }
+    
+    # now apply the pattern to layers below unsupported surfaces
+    my (@a, @b) = ();
+    for (my $i = $#{$self->layers}; $i >=0; $i--) {
+        my $layer = $self->layers->[$i];
+        my @c = ();
+        if (@b) {
+            @c = @{diff_ex(
+                [ map @$_, @b ],
+                [ map @$_, map $_->expolygon->offset_ex(scale $Slic3r::flow_width), @{$layer->slices} ],
+            )};
+            $layer->support_fills(Slic3r::ExtrusionPath::Collection->new);
+            foreach my $expolygon (@c) {
+                push @{$layer->support_fills->paths}, map $_->clip_with_expolygon($expolygon), @$support_pattern;
+            }
+        }
+        @b = @{union_ex([ map @$_, @c, @a ])};
+        @a = map $_->expolygon->offset_ex(scale 2),
+            grep $_->surface_type eq 'bottom' && !defined $_->bridge_angle,
+            @{$layer->slices};
+    }
+}
+
 sub export_gcode {
     my $self = shift;
     my ($file) = @_;
@@ -522,6 +591,12 @@ sub export_gcode {
                 print $fh $extruder->extrude_path($_, 'fill') 
                     for $fill->shortest_path($extruder->last_pos);
             }
+            
+            # extrude support material
+            if ($layer->support_fills) {
+                print $fh $extruder->extrude_path($_, 'support material') 
+                    for $layer->support_fills->shortest_path($extruder->last_pos);
+            }
         }
     }
     
diff --git a/lib/Slic3r/Skein.pm b/lib/Slic3r/Skein.pm
index 7719274e..0afd87a8 100644
--- a/lib/Slic3r/Skein.pm
+++ b/lib/Slic3r/Skein.pm
@@ -35,10 +35,6 @@ sub go {
         $print = Slic3r::Print->new_from_mesh($mesh);
     }
     
-    # make skirt
-    $self->status_cb->(15, "Generating skirt...");
-    $print->extrude_skirt;
-    
     # make perimeters
     # this will add a set of extrusion loops to each layer
     # as well as generate infill boundaries
@@ -118,6 +114,16 @@ sub go {
     # free memory
     @{$_->fill_surfaces} = () for @{$print->layers};
     
+    # generate support material
+    if ($Slic3r::support_material) {
+        $self->status_cb->(85, "Generating support material...");
+        $print->generate_support_material;
+    }
+    
+    # make skirt
+    $self->status_cb->(88, "Generating skirt...");
+    $print->extrude_skirt;
+    
     # output everything to a GCODE file
     $self->status_cb->(90, "Exporting GCODE...");
     $print->export_gcode($self->expanded_output_filepath);
diff --git a/slic3r.pl b/slic3r.pl
index e1366e79..7d534c02 100755
--- a/slic3r.pl
+++ b/slic3r.pl
@@ -167,6 +167,7 @@ Usage: slic3r.pl [ OPTIONS ] file.stl
     --end-gcode         Load final gcode from the supplied file. This will overwrite 
                         the default commands (turn off temperature [M104 S0],
                         home X axis [G28 X], disable motors [M84]).
+    --support-material  Generate support material for overhangs
   
   Retraction options:
     --retract-length    Length of retraction in mm when pausing extrusion