diff --git a/src/gallium/drivers/r600/evergreen_state.c b/src/gallium/drivers/r600/evergreen_state.c
index f0b04f004fb..edd886b96f2 100644
--- a/src/gallium/drivers/r600/evergreen_state.c
+++ b/src/gallium/drivers/r600/evergreen_state.c
@@ -1692,7 +1692,7 @@ static void evergreen_emit_framebuffer_state(struct r600_context *rctx, struct r
 		evergreen_emit_msaa_state(rctx, rctx->framebuffer.nr_samples, rctx->ps_iter_samples);
 	} else {
 		cayman_emit_msaa_sample_locs(cs, rctx->framebuffer.nr_samples);
-		cayman_emit_msaa_config(cs, rctx->framebuffer.nr_samples, rctx->ps_iter_samples);
+		cayman_emit_msaa_config(cs, rctx->framebuffer.nr_samples, rctx->ps_iter_samples, 0);
 	}
 }
 
diff --git a/src/gallium/drivers/radeon/cayman_msaa.c b/src/gallium/drivers/radeon/cayman_msaa.c
index 47fc5c497f1..12a5f604755 100644
--- a/src/gallium/drivers/radeon/cayman_msaa.c
+++ b/src/gallium/drivers/radeon/cayman_msaa.c
@@ -195,9 +195,12 @@ void cayman_emit_msaa_sample_locs(struct radeon_winsys_cs *cs, int nr_samples)
 }
 
 void cayman_emit_msaa_config(struct radeon_winsys_cs *cs, int nr_samples,
-			     int ps_iter_samples)
+			     int ps_iter_samples, int overrast_samples)
 {
-	if (nr_samples > 1) {
+	int setup_samples = nr_samples > 1 ? nr_samples :
+			    overrast_samples > 1 ? overrast_samples : 0;
+
+	if (setup_samples > 1) {
 		/* indexed by log2(nr_samples) */
 		unsigned max_dist[] = {
 			0,
@@ -206,8 +209,7 @@ void cayman_emit_msaa_config(struct radeon_winsys_cs *cs, int nr_samples,
 			cm_max_dist_8x,
 			cm_max_dist_16x
 		};
-
-		unsigned log_samples = util_logbase2(nr_samples);
+		unsigned log_samples = util_logbase2(setup_samples);
 		unsigned log_ps_iter_samples =
 			util_logbase2(util_next_power_of_two(ps_iter_samples));
 
@@ -218,15 +220,23 @@ void cayman_emit_msaa_config(struct radeon_winsys_cs *cs, int nr_samples,
 			    S_028BE0_MAX_SAMPLE_DIST(max_dist[log_samples]) |
 			    S_028BE0_MSAA_EXPOSED_SAMPLES(log_samples)); /* CM_R_028BE0_PA_SC_AA_CONFIG */
 
-		r600_write_context_reg(cs, CM_R_028804_DB_EQAA,
-				       S_028804_MAX_ANCHOR_SAMPLES(log_samples) |
-				       S_028804_PS_ITER_SAMPLES(log_ps_iter_samples) |
-				       S_028804_MASK_EXPORT_NUM_SAMPLES(log_samples) |
-				       S_028804_ALPHA_TO_MASK_NUM_SAMPLES(log_samples) |
-				       S_028804_HIGH_QUALITY_INTERSECTIONS(1) |
-				       S_028804_STATIC_ANCHOR_ASSOCIATIONS(1));
-		r600_write_context_reg(cs, EG_R_028A4C_PA_SC_MODE_CNTL_1,
-				     EG_S_028A4C_PS_ITER_SAMPLE(ps_iter_samples > 1));
+		if (nr_samples > 1) {
+			r600_write_context_reg(cs, CM_R_028804_DB_EQAA,
+					       S_028804_MAX_ANCHOR_SAMPLES(log_samples) |
+					       S_028804_PS_ITER_SAMPLES(log_ps_iter_samples) |
+					       S_028804_MASK_EXPORT_NUM_SAMPLES(log_samples) |
+					       S_028804_ALPHA_TO_MASK_NUM_SAMPLES(log_samples) |
+					       S_028804_HIGH_QUALITY_INTERSECTIONS(1) |
+					       S_028804_STATIC_ANCHOR_ASSOCIATIONS(1));
+			r600_write_context_reg(cs, EG_R_028A4C_PA_SC_MODE_CNTL_1,
+					     EG_S_028A4C_PS_ITER_SAMPLE(ps_iter_samples > 1));
+		} else if (overrast_samples > 1) {
+			r600_write_context_reg(cs, CM_R_028804_DB_EQAA,
+					       S_028804_HIGH_QUALITY_INTERSECTIONS(1) |
+					       S_028804_STATIC_ANCHOR_ASSOCIATIONS(1) |
+					       S_028804_OVERRASTERIZATION_AMOUNT(log_samples));
+			r600_write_context_reg(cs, EG_R_028A4C_PA_SC_MODE_CNTL_1, 0);
+		}
 	} else {
 		r600_write_context_reg_seq(cs, CM_R_028BDC_PA_SC_LINE_CNTL, 2);
 		radeon_emit(cs, S_028BDC_LAST_PIXEL(1)); /* CM_R_028BDC_PA_SC_LINE_CNTL */
diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h b/src/gallium/drivers/radeon/r600_pipe_common.h
index 43efaa34b4c..a08d08cdf14 100644
--- a/src/gallium/drivers/radeon/r600_pipe_common.h
+++ b/src/gallium/drivers/radeon/r600_pipe_common.h
@@ -526,7 +526,7 @@ void cayman_get_sample_position(struct pipe_context *ctx, unsigned sample_count,
 void cayman_init_msaa(struct pipe_context *ctx);
 void cayman_emit_msaa_sample_locs(struct radeon_winsys_cs *cs, int nr_samples);
 void cayman_emit_msaa_config(struct radeon_winsys_cs *cs, int nr_samples,
-			     int ps_iter_samples);
+			     int ps_iter_samples, int overrast_samples);
 
 
 /* Inline helpers. */
diff --git a/src/gallium/drivers/radeon/r600d_common.h b/src/gallium/drivers/radeon/r600d_common.h
index ba29fd0c2d6..74c8d8782a6 100644
--- a/src/gallium/drivers/radeon/r600d_common.h
+++ b/src/gallium/drivers/radeon/r600d_common.h
@@ -177,6 +177,8 @@
 #define   S_028804_INTERPOLATE_SRC_Z(x)			(((x) & 0x1) << 19)
 #define   S_028804_STATIC_ANCHOR_ASSOCIATIONS(x)	(((x) & 0x1) << 20)
 #define   S_028804_ALPHA_TO_MASK_EQAA_DISABLE(x)	(((x) & 0x1) << 21)
+#define   S_028804_OVERRASTERIZATION_AMOUNT(x)		(((x) & 0x7) << 24)
+#define   S_028804_ENABLE_POSTZ_OVERRASTERIZATION(x)	(((x) & 0x1) << 27)
 #define CM_R_028BDC_PA_SC_LINE_CNTL                  0x28bdc
 #define   S_028BDC_EXPAND_LINE_WIDTH(x)                (((x) & 0x1) << 9)
 #define   G_028BDC_EXPAND_LINE_WIDTH(x)                (((x) >> 9) & 0x1)
diff --git a/src/gallium/drivers/radeonsi/si_state.c b/src/gallium/drivers/radeonsi/si_state.c
index 5de31c03192..b20042ce831 100644
--- a/src/gallium/drivers/radeonsi/si_state.c
+++ b/src/gallium/drivers/radeonsi/si_state.c
@@ -2206,7 +2206,7 @@ static void si_emit_msaa_config(struct r600_common_context *rctx, struct r600_at
 	struct radeon_winsys_cs *cs = sctx->b.rings.gfx.cs;
 
 	cayman_emit_msaa_config(cs, sctx->framebuffer.nr_samples,
-				sctx->ps_iter_samples);
+				sctx->ps_iter_samples, 0);
 }
 
 const struct r600_atom si_atom_msaa_config = { si_emit_msaa_config, 10 }; /* number of CS dwords */