diff --git a/libavcodec/libx265.c b/libavcodec/libx265.c
index 447e6da25f..8d366f51ab 100644
--- a/libavcodec/libx265.c
+++ b/libavcodec/libx265.c
@@ -28,9 +28,11 @@
 #include <float.h>
 
 #include "libavutil/avassert.h"
+#include "libavutil/bprint.h"
 #include "libavutil/buffer.h"
 #include "libavutil/internal.h"
 #include "libavutil/common.h"
+#include "libavutil/mastering_display_metadata.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "avcodec.h"
@@ -179,6 +181,85 @@ static av_cold int libx265_param_parse_int(AVCodecContext *avctx,
     return 0;
 }
 
+static int handle_mdcv(const AVClass **avcl, const x265_api *api,
+                       x265_param *params,
+                       const AVMasteringDisplayMetadata *mdcv)
+{
+    int ret = AVERROR_BUG;
+    AVBPrint buf;
+    av_bprint_init(&buf, 0, AV_BPRINT_SIZE_AUTOMATIC);
+
+    // G(%hu,%hu)B(%hu,%hu)R(%hu,%hu)WP(%hu,%hu)L(%u,%u)
+    av_bprintf(
+        &buf,
+        "G(%"PRId64",%"PRId64")B(%"PRId64",%"PRId64")R(%"PRId64",%"PRId64")"
+        "WP(%"PRId64",%"PRId64")L(%"PRId64",%"PRId64")",
+        av_rescale_q(1, mdcv->display_primaries[1][0], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->display_primaries[1][1], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->display_primaries[2][0], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->display_primaries[2][1], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->display_primaries[0][0], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->display_primaries[0][1], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->white_point[0], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->white_point[1], (AVRational){ 1, 50000 }),
+        av_rescale_q(1, mdcv->max_luminance,  (AVRational){ 1, 10000 }),
+        av_rescale_q(1, mdcv->min_luminance,  (AVRational){ 1, 10000 }));
+
+    if (!av_bprint_is_complete(&buf)) {
+        av_log(avcl, AV_LOG_ERROR,
+          "MDCV string too long for its available space!\n");
+        ret = AVERROR(ENOMEM);
+        goto end;
+    }
+
+    if (api->param_parse(params, "master-display", buf.str) ==
+            X265_PARAM_BAD_VALUE) {
+        av_log(avcl, AV_LOG_ERROR,
+               "Invalid value \"%s\" for param \"master-display\".\n",
+               buf.str);
+        ret = AVERROR(EINVAL);
+        goto end;
+    }
+
+    ret = 0;
+
+end:
+    av_bprint_finalize(&buf, NULL);
+
+    return ret;
+}
+
+static int handle_side_data(AVCodecContext *avctx, const x265_api *api,
+                            x265_param *params)
+{
+    const AVFrameSideData *cll_sd =
+        av_frame_side_data_get(
+            (const AVFrameSideData **)avctx->frame_side_data,
+            avctx->nb_frame_side_data, AV_FRAME_DATA_CONTENT_LIGHT_LEVEL);
+    const AVFrameSideData *mdcv_sd =
+        av_frame_side_data_get(
+            (const AVFrameSideData **)avctx->frame_side_data,
+            avctx->nb_frame_side_data, AV_FRAME_DATA_MASTERING_DISPLAY_METADATA);
+
+    if (cll_sd) {
+        const AVContentLightMetadata *cll =
+            (AVContentLightMetadata *)cll_sd->data;
+
+        params->maxCLL  = cll->MaxCLL;
+        params->maxFALL = cll->MaxFALL;
+    }
+
+    if (mdcv_sd) {
+        int ret = handle_mdcv(
+            &avctx->av_class, api, params,
+            (AVMasteringDisplayMetadata *)mdcv_sd->data);
+        if (ret < 0)
+            return ret;
+    }
+
+    return 0;
+}
+
 static av_cold int libx265_encode_init(AVCodecContext *avctx)
 {
     libx265Context *ctx = avctx->priv_data;
@@ -339,6 +420,13 @@ FF_ENABLE_DEPRECATION_WARNINGS
         return AVERROR_BUG;
     }
 
+    ret = handle_side_data(avctx, ctx->api, ctx->params);
+    if (ret < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Failed handling side data! (%s)\n",
+               av_err2str(ret));
+        return ret;
+    }
+
     if (ctx->crf >= 0) {
         char crf[6];
 
diff --git a/tests/fate/enc_external.mak b/tests/fate/enc_external.mak
index 4095a4b51a..30021efbcd 100644
--- a/tests/fate/enc_external.mak
+++ b/tests/fate/enc_external.mak
@@ -12,5 +12,10 @@ FATE_ENC_EXTERNAL-$(call ENCDEC, LIBX264 HEVC, MOV, LIBX264_HDR10 HEVC_DEMUXER H
 fate-libx264-hdr10: CMD = enc_external $(TARGET_SAMPLES)/hevc/hdr10_plus_h265_sample.hevc \
     mp4 "-c:v libx264" "-show_frames -show_entries frame=side_data_list -of flat"
 
+# test for x265 MDCV and CLL passthrough during encoding
+FATE_ENC_EXTERNAL-$(call ENCDEC, LIBX265 HEVC, MOV, HEVC_DEMUXER) += fate-libx265-hdr10
+fate-libx265-hdr10: CMD = enc_external $(TARGET_SAMPLES)/hevc/hdr10_plus_h265_sample.hevc \
+    mp4 "-c:v libx265" "-show_frames -show_entries frame=side_data_list -of flat"
+
 FATE_SAMPLES_FFMPEG_FFPROBE += $(FATE_ENC_EXTERNAL-yes)
 fate-enc-external: $(FATE_ENC_EXTERNAL-yes)
diff --git a/tests/ref/fate/libx265-hdr10 b/tests/ref/fate/libx265-hdr10
new file mode 100644
index 0000000000..571c837cac
--- /dev/null
+++ b/tests/ref/fate/libx265-hdr10
@@ -0,0 +1,16 @@
+frames.frame.0.side_data_list.side_data.0.side_data_type="H.26[45] User Data Unregistered SEI message"
+frames.frame.0.side_data_list.side_data.1.side_data_type="H.26[45] User Data Unregistered SEI message"
+frames.frame.0.side_data_list.side_data.2.side_data_type="Mastering display metadata"
+frames.frame.0.side_data_list.side_data.2.red_x="13250/50000"
+frames.frame.0.side_data_list.side_data.2.red_y="34500/50000"
+frames.frame.0.side_data_list.side_data.2.green_x="7500/50000"
+frames.frame.0.side_data_list.side_data.2.green_y="3000/50000"
+frames.frame.0.side_data_list.side_data.2.blue_x="34000/50000"
+frames.frame.0.side_data_list.side_data.2.blue_y="16000/50000"
+frames.frame.0.side_data_list.side_data.2.white_point_x="15635/50000"
+frames.frame.0.side_data_list.side_data.2.white_point_y="16450/50000"
+frames.frame.0.side_data_list.side_data.2.min_luminance="50/10000"
+frames.frame.0.side_data_list.side_data.2.max_luminance="10000000/10000"
+frames.frame.0.side_data_list.side_data.3.side_data_type="Content light level metadata"
+frames.frame.0.side_data_list.side_data.3.max_content=1000
+frames.frame.0.side_data_list.side_data.3.max_average=200
