diff --git a/intern/cycles/blender/addon/properties.py b/intern/cycles/blender/addon/properties.py
index 977d7f75bb7..ede3ece5bce 100644
--- a/intern/cycles/blender/addon/properties.py
+++ b/intern/cycles/blender/addon/properties.py
@@ -266,6 +266,13 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
                 description="Sample all lights (for indirect samples), rather than randomly picking one",
                 default=True,
                 )
+        cls.light_sampling_threshold = FloatProperty(
+                name="Light Sampling Threshold",
+                description="Probabilistically terminate light samples when the light contribution is below this threshold (more noise but faster rendering). "
+                            "Zero disables the test and never ignores lights.",
+                min=0.0, max=1.0,
+                default=0.05,
+                )
 
         cls.caustics_reflective = BoolProperty(
                 name="Reflective Caustics",
diff --git a/intern/cycles/blender/addon/ui.py b/intern/cycles/blender/addon/ui.py
index 52872d2b83f..4942a71ce4d 100644
--- a/intern/cycles/blender/addon/ui.py
+++ b/intern/cycles/blender/addon/ui.py
@@ -166,6 +166,7 @@ class CyclesRender_PT_sampling(CyclesButtonsPanel, Panel):
 
         sub.prop(cscene, "sample_clamp_direct")
         sub.prop(cscene, "sample_clamp_indirect")
+        sub.prop(cscene, "light_sampling_threshold")
 
         if cscene.progressive == 'PATH' or use_branched_path(context) is False:
             col = split.column()
diff --git a/intern/cycles/blender/blender_sync.cpp b/intern/cycles/blender/blender_sync.cpp
index 4ca202ac40d..bc5c3bb8096 100644
--- a/intern/cycles/blender/blender_sync.cpp
+++ b/intern/cycles/blender/blender_sync.cpp
@@ -284,6 +284,7 @@ void BlenderSync::sync_integrator()
 
 	integrator->sample_all_lights_direct = get_boolean(cscene, "sample_all_lights_direct");
 	integrator->sample_all_lights_indirect = get_boolean(cscene, "sample_all_lights_indirect");
+	integrator->light_sampling_threshold = get_float(cscene, "light_sampling_threshold");
 
 	int diffuse_samples = get_int(cscene, "diffuse_samples");
 	int glossy_samples = get_int(cscene, "glossy_samples");
diff --git a/intern/cycles/kernel/kernel_accumulate.h b/intern/cycles/kernel/kernel_accumulate.h
index 623c1dcaaa1..6c3ee6b8098 100644
--- a/intern/cycles/kernel/kernel_accumulate.h
+++ b/intern/cycles/kernel/kernel_accumulate.h
@@ -96,7 +96,7 @@ ccl_device_inline bool bsdf_eval_is_zero(BsdfEval *eval)
 	}
 }
 
-ccl_device_inline void bsdf_eval_mul(BsdfEval *eval, float3 value)
+ccl_device_inline void bsdf_eval_mul(BsdfEval *eval, float value)
 {
 #ifdef __PASSES__
 	if(eval->use_light_pass) {
@@ -115,6 +115,36 @@ ccl_device_inline void bsdf_eval_mul(BsdfEval *eval, float3 value)
 	}
 }
 
+ccl_device_inline void bsdf_eval_mul3(BsdfEval *eval, float3 value)
+{
+#ifdef __PASSES__
+	if(eval->use_light_pass) {
+		eval->diffuse *= value;
+		eval->glossy *= value;
+		eval->transmission *= value;
+		eval->subsurface *= value;
+		eval->scatter *= value;
+
+		/* skipping transparent, this function is used by for eval(), will be zero then */
+	}
+	else
+		eval->diffuse *= value;
+#else
+	eval->diffuse *= value;
+#endif
+}
+
+ccl_device_inline float3 bsdf_eval_sum(BsdfEval *eval)
+{
+#ifdef __PASSES__
+	if(eval->use_light_pass) {
+		return eval->diffuse + eval->glossy + eval->transmission + eval->subsurface + eval->scatter;
+	}
+	else
+#endif
+	return eval->diffuse;
+}
+
 /* Path Radiance
  *
  * We accumulate different render passes separately. After summing at the end
@@ -193,8 +223,7 @@ ccl_device_inline void path_radiance_bsdf_bounce(PathRadiance *L, ccl_addr_space
 		}
 		else {
 			/* transparent bounce before first hit, or indirectly visible through BSDF */
-			float3 sum = (bsdf_eval->diffuse + bsdf_eval->glossy + bsdf_eval->transmission + bsdf_eval->transparent +
-						  bsdf_eval->subsurface + bsdf_eval->scatter) * inverse_pdf;
+			float3 sum = (bsdf_eval_sum(bsdf_eval) + bsdf_eval->transparent) * inverse_pdf;
 			*throughput *= sum;
 		}
 	}
@@ -264,8 +293,7 @@ ccl_device_inline void path_radiance_accum_light(PathRadiance *L, float3 through
 		}
 		else {
 			/* indirectly visible lighting after BSDF bounce */
-			float3 sum = bsdf_eval->diffuse + bsdf_eval->glossy + bsdf_eval->transmission + bsdf_eval->subsurface + bsdf_eval->scatter;
-			L->indirect += throughput*sum*shadow;
+			L->indirect += throughput*bsdf_eval_sum(bsdf_eval)*shadow;
 		}
 	}
 	else
diff --git a/intern/cycles/kernel/kernel_emission.h b/intern/cycles/kernel/kernel_emission.h
index 9e4a631b998..8c7c651a053 100644
--- a/intern/cycles/kernel/kernel_emission.h
+++ b/intern/cycles/kernel/kernel_emission.h
@@ -94,7 +94,8 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg,
                                          ccl_addr_space PathState *state,
                                          Ray *ray,
                                          BsdfEval *eval,
-                                         bool *is_lamp)
+                                         bool *is_lamp,
+                                         float rand_terminate)
 {
 	if(ls->pdf == 0.0f)
 		return false;
@@ -134,7 +135,7 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg,
 	shader_bsdf_eval(kg, sd, ls->D, eval, ls->pdf, ls->shader & SHADER_USE_MIS);
 #endif
 
-	bsdf_eval_mul(eval, light_eval/ls->pdf);
+	bsdf_eval_mul3(eval, light_eval/ls->pdf);
 
 #ifdef __PASSES__
 	/* use visibility flag to skip lights */
@@ -155,6 +156,16 @@ ccl_device_noinline bool direct_emission(KernelGlobals *kg,
 	if(bsdf_eval_is_zero(eval))
 		return false;
 
+	if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) {
+		float probability = max3(bsdf_eval_sum(eval)) * kernel_data.integrator.light_inv_rr_threshold;
+		if(probability < 1.0f) {
+			if(rand_terminate >= probability) {
+				return false;
+			}
+			bsdf_eval_mul(eval, 1.0f / probability);
+		}
+	}
+
 	if(ls->shader & SHADER_CAST_SHADOW) {
 		/* setup ray */
 		bool transmit = (dot(ccl_fetch(sd, Ng), ls->D) < 0.0f);
diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index 7558fb94478..7ef79815ad5 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -851,7 +851,6 @@ ccl_device_inline float4 kernel_path_integrate(KernelGlobals *kg,
 		}
 		else if(probability != 1.0f) {
 			float terminate = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_TERMINATE);
-
 			if(terminate >= probability)
 				break;
 
diff --git a/intern/cycles/kernel/kernel_path_surface.h b/intern/cycles/kernel/kernel_path_surface.h
index 45f0f1cbfaa..fea503d06e5 100644
--- a/intern/cycles/kernel/kernel_path_surface.h
+++ b/intern/cycles/kernel/kernel_path_surface.h
@@ -49,6 +49,7 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 			for(int j = 0; j < num_samples; j++) {
 				float light_u, light_v;
 				path_branched_rng_2D(kg, &lamp_rng, state, j, num_samples, PRNG_LIGHT_U, &light_u, &light_v);
+				float terminate = path_branched_rng_light_termination(kg, &lamp_rng, state, j, num_samples);
 
 				LightSample ls;
 				if(lamp_light_sample(kg, i, light_u, light_v, ccl_fetch(sd, P), &ls)) {
@@ -57,7 +58,7 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 					if(kernel_data.integrator.pdf_triangles != 0.0f)
 						ls.pdf *= 2.0f;
 
-					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 						/* trace shadow ray */
 						float3 shadow;
 
@@ -79,6 +80,7 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 				float light_t = path_branched_rng_1D(kg, rng, state, j, num_samples, PRNG_LIGHT);
 				float light_u, light_v;
 				path_branched_rng_2D(kg, rng, state, j, num_samples, PRNG_LIGHT_U, &light_u, &light_v);
+				float terminate = path_branched_rng_light_termination(kg, rng, state, j, num_samples);
 
 				/* only sample triangle lights */
 				if(kernel_data.integrator.num_all_lights)
@@ -90,7 +92,7 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 					if(kernel_data.integrator.num_all_lights)
 						ls.pdf *= 2.0f;
 
-					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 						/* trace shadow ray */
 						float3 shadow;
 
@@ -108,11 +110,12 @@ ccl_device_noinline void kernel_branched_path_surface_connect_light(KernelGlobal
 		float light_t = path_state_rng_1D(kg, rng, state, PRNG_LIGHT);
 		float light_u, light_v;
 		path_state_rng_2D(kg, rng, state, PRNG_LIGHT_U, &light_u, &light_v);
+		float terminate = path_state_rng_light_termination(kg, rng, state);
 
 		LightSample ls;
 		if(light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls)) {
 			/* sample random light */
-			if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+			if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 				/* trace shadow ray */
 				float3 shadow;
 
@@ -210,7 +213,8 @@ ccl_device_inline void kernel_path_surface_connect_light(KernelGlobals *kg, ccl_
 
 	LightSample ls;
 	if(light_sample(kg, light_t, light_u, light_v, ccl_fetch(sd, time), ccl_fetch(sd, P), state->bounce, &ls)) {
-		if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+		float terminate = path_state_rng_light_termination(kg, rng, state);
+		if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 			/* trace shadow ray */
 			float3 shadow;
 
diff --git a/intern/cycles/kernel/kernel_path_volume.h b/intern/cycles/kernel/kernel_path_volume.h
index 5ee1912c913..3d3b7385d8b 100644
--- a/intern/cycles/kernel/kernel_path_volume.h
+++ b/intern/cycles/kernel/kernel_path_volume.h
@@ -48,7 +48,8 @@ ccl_device_inline void kernel_path_volume_connect_light(
 
 	if(light_sample(kg, light_t, light_u, light_v, sd->time, sd->P, state->bounce, &ls))
 	{
-		if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+		float terminate = path_state_rng_light_termination(kg, rng, state);
+		if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 			/* trace shadow ray */
 			float3 shadow;
 
@@ -161,7 +162,8 @@ ccl_device void kernel_branched_path_volume_connect_light(KernelGlobals *kg, RNG
 					if(kernel_data.integrator.pdf_triangles != 0.0f)
 						ls.pdf *= 2.0f;
 
-					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+					float terminate = path_branched_rng_light_termination(kg, rng, state, j, num_samples);
+					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 						/* trace shadow ray */
 						float3 shadow;
 
@@ -209,7 +211,8 @@ ccl_device void kernel_branched_path_volume_connect_light(KernelGlobals *kg, RNG
 					if(kernel_data.integrator.num_all_lights)
 						ls.pdf *= 2.0f;
 
-					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+					float terminate = path_branched_rng_light_termination(kg, rng, state, j, num_samples);
+					if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 						/* trace shadow ray */
 						float3 shadow;
 
@@ -246,7 +249,8 @@ ccl_device void kernel_branched_path_volume_connect_light(KernelGlobals *kg, RNG
 		/* todo: split up light_sample so we don't have to call it again with new position */
 		if(light_sample(kg, light_t, light_u, light_v, sd->time, sd->P, state->bounce, &ls)) {
 			/* sample random light */
-			if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp)) {
+			float terminate = path_state_rng_light_termination(kg, rng, state);
+			if(direct_emission(kg, sd, emission_sd, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 				/* trace shadow ray */
 				float3 shadow;
 
diff --git a/intern/cycles/kernel/kernel_random.h b/intern/cycles/kernel/kernel_random.h
index 4a76ffddbe7..2372b07d974 100644
--- a/intern/cycles/kernel/kernel_random.h
+++ b/intern/cycles/kernel/kernel_random.h
@@ -300,6 +300,23 @@ ccl_device_inline void path_branched_rng_2D(KernelGlobals *kg, ccl_addr_space RN
 	path_rng_2D(kg, rng, state->sample*num_branches + branch, state->num_samples*num_branches, state->rng_offset + dimension, fx, fy);
 }
 
+/* Utitility functions to get light termination value, since it might not be needed in many cases. */
+ccl_device_inline float path_state_rng_light_termination(KernelGlobals *kg, ccl_addr_space RNG *rng, const PathState *state)
+{
+	if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) {
+		return path_state_rng_1D_for_decision(kg, rng, state, PRNG_LIGHT_TERMINATE);
+	}
+	return 0.0f;
+}
+
+ccl_device_inline float path_branched_rng_light_termination(KernelGlobals *kg, ccl_addr_space RNG *rng, const PathState *state, int branch, int num_branches)
+{
+	if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) {
+		return path_branched_rng_1D_for_decision(kg, rng, state, branch, num_branches, PRNG_LIGHT_TERMINATE);
+	}
+	return 0.0f;
+}
+
 ccl_device_inline void path_state_branch(PathState *state, int branch, int num_branches)
 {
 	/* path is splitting into a branch, adjust so that each branch
diff --git a/intern/cycles/kernel/kernel_shader.h b/intern/cycles/kernel/kernel_shader.h
index a8070a133de..b4b980c4e90 100644
--- a/intern/cycles/kernel/kernel_shader.h
+++ b/intern/cycles/kernel/kernel_shader.h
@@ -572,7 +572,7 @@ void shader_bsdf_eval(KernelGlobals *kg,
 		_shader_bsdf_multi_eval(kg, sd, omega_in, &pdf, -1, eval, 0.0f, 0.0f);
 		if(use_mis) {
 			float weight = power_heuristic(light_pdf, pdf);
-			bsdf_eval_mul(eval, make_float3(weight, weight, weight));
+			bsdf_eval_mul(eval, weight);
 		}
 	}
 }
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 91b86618745..a6c31d4a518 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -250,7 +250,7 @@ enum PathTraceDimension {
 	PRNG_LIGHT = 3,
 	PRNG_LIGHT_U = 4,
 	PRNG_LIGHT_V = 5,
-	PRNG_UNUSED_3 = 6,
+	PRNG_LIGHT_TERMINATE = 6,
 	PRNG_TERMINATE = 7,
 
 #ifdef __VOLUME__
@@ -1123,8 +1123,9 @@ typedef struct KernelIntegrator {
 	float volume_step_size;
 	int volume_samples;
 
+	float light_inv_rr_threshold;
+
 	int pad1;
-	int pad2;
 } KernelIntegrator;
 static_assert_align(KernelIntegrator, 16);
 
diff --git a/intern/cycles/kernel/split/kernel_direct_lighting.h b/intern/cycles/kernel/split/kernel_direct_lighting.h
index 6ad736fc2c1..82ca18829d3 100644
--- a/intern/cycles/kernel/split/kernel_direct_lighting.h
+++ b/intern/cycles/kernel/split/kernel_direct_lighting.h
@@ -72,6 +72,7 @@ ccl_device char kernel_direct_lighting(
 			float light_t = path_state_rng_1D(kg, rng, state, PRNG_LIGHT);
 			float light_u, light_v;
 			path_state_rng_2D(kg, rng, state, PRNG_LIGHT_U, &light_u, &light_v);
+			float terminate = path_state_rng_light_termination(kg, rng, state);
 
 			LightSample ls;
 			if(light_sample(kg,
@@ -88,7 +89,7 @@ ccl_device char kernel_direct_lighting(
 
 				BsdfEval L_light;
 				bool is_lamp;
-				if(direct_emission(kg, sd, kg->sd_input, &ls, state, &light_ray, &L_light, &is_lamp)) {
+				if(direct_emission(kg, sd, kg->sd_input, &ls, state, &light_ray, &L_light, &is_lamp, terminate)) {
 					/* Write intermediate data to global memory to access from
 					 * the next kernel.
 					 */
diff --git a/intern/cycles/render/integrator.cpp b/intern/cycles/render/integrator.cpp
index 63914e57319..a9a33d2e789 100644
--- a/intern/cycles/render/integrator.cpp
+++ b/intern/cycles/render/integrator.cpp
@@ -65,6 +65,7 @@ NODE_DEFINE(Integrator)
 
 	SOCKET_BOOLEAN(sample_all_lights_direct, "Sample All Lights Direct", true);
 	SOCKET_BOOLEAN(sample_all_lights_indirect, "Sample All Lights Indirect", true);
+	SOCKET_FLOAT(light_sampling_threshold, "Light Sampling Threshold", 0.05f);
 
 	static NodeEnum method_enum;
 	method_enum.insert("path", PATH);
@@ -164,6 +165,13 @@ void Integrator::device_update(Device *device, DeviceScene *dscene, Scene *scene
 	kintegrator->sampling_pattern = sampling_pattern;
 	kintegrator->aa_samples = aa_samples;
 
+	if(light_sampling_threshold > 0.0f) {
+		kintegrator->light_inv_rr_threshold = 1.0f / light_sampling_threshold;
+	}
+	else {
+		kintegrator->light_inv_rr_threshold = 0.0f;
+	}
+
 	/* sobol directions table */
 	int max_samples = 1;
 
diff --git a/intern/cycles/render/integrator.h b/intern/cycles/render/integrator.h
index 39eaaf246d4..17fdd0ef1db 100644
--- a/intern/cycles/render/integrator.h
+++ b/intern/cycles/render/integrator.h
@@ -64,8 +64,10 @@ public:
 	int mesh_light_samples;
 	int subsurface_samples;
 	int volume_samples;
+
 	bool sample_all_lights_direct;
 	bool sample_all_lights_indirect;
+	float light_sampling_threshold;
 
 	enum Method {
 		BRANCHED_PATH = 0,
diff --git a/intern/cycles/util/util_math.h b/intern/cycles/util/util_math.h
index e2abfcde702..3f4d3e06c0b 100644
--- a/intern/cycles/util/util_math.h
+++ b/intern/cycles/util/util_math.h
@@ -162,6 +162,11 @@ ccl_device_inline float max4(float a, float b, float c, float d)
 	return max(max(a, b), max(c, d));
 }
 
+ccl_device_inline float max3(float3 a)
+{
+	return max(max(a.x, a.y), a.z);
+}
+
 #ifndef __KERNEL_OPENCL__
 
 ccl_device_inline int clamp(int a, int mn, int mx)