--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -110,7 +110,12 @@ typedef struct {
     ngx_http_proxy_vars_t          vars;
     off_t                          internal_body_length;
 
-    ngx_uint_t                     head;  /* unsigned  head:1 */
+    ngx_chain_t                   *free;
+    ngx_chain_t                   *busy;
+
+    unsigned                       head:1;
+    unsigned                       internal_chunked:1;
+    unsigned                       header_sent:1;
 } ngx_http_proxy_ctx_t;
 
 
@@ -121,6 +126,7 @@ static ngx_int_t ngx_http_proxy_create_k
 #endif
 static ngx_int_t ngx_http_proxy_create_request(ngx_http_request_t *r);
 static ngx_int_t ngx_http_proxy_reinit_request(ngx_http_request_t *r);
+static ngx_int_t ngx_http_proxy_body_output_filter(void *data, ngx_chain_t *in);
 static ngx_int_t ngx_http_proxy_process_status_line(ngx_http_request_t *r);
 static ngx_int_t ngx_http_proxy_process_header(ngx_http_request_t *r);
 static ngx_int_t ngx_http_proxy_input_filter_init(void *data);
@@ -146,6 +152,8 @@ static ngx_int_t
 static ngx_int_t
     ngx_http_proxy_internal_body_length_variable(ngx_http_request_t *r,
     ngx_http_variable_value_t *v, uintptr_t data);
+static ngx_int_t ngx_http_proxy_internal_chunked_variable(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data);
 static ngx_int_t ngx_http_proxy_rewrite_redirect(ngx_http_request_t *r,
     ngx_table_elt_t *h, size_t prefix);
 static ngx_int_t ngx_http_proxy_rewrite_cookie(ngx_http_request_t *r,
@@ -728,8 +736,8 @@ static ngx_keyval_t  ngx_http_proxy_head
     { ngx_string("Host"), ngx_string("$proxy_host") },
     { ngx_string("Connection"), ngx_string("close") },
     { ngx_string("Content-Length"), ngx_string("$proxy_internal_body_length") },
+    { ngx_string("Transfer-Encoding"), ngx_string("$proxy_internal_chunked") },
     { ngx_string("TE"), ngx_string("") },
-    { ngx_string("Transfer-Encoding"), ngx_string("") },
     { ngx_string("Keep-Alive"), ngx_string("") },
     { ngx_string("Expect"), ngx_string("") },
     { ngx_string("Upgrade"), ngx_string("") },
@@ -756,8 +764,8 @@ static ngx_keyval_t  ngx_http_proxy_cach
     { ngx_string("Host"), ngx_string("$proxy_host") },
     { ngx_string("Connection"), ngx_string("close") },
     { ngx_string("Content-Length"), ngx_string("$proxy_internal_body_length") },
+    { ngx_string("Transfer-Encoding"), ngx_string("$proxy_internal_chunked") },
     { ngx_string("TE"), ngx_string("") },
-    { ngx_string("Transfer-Encoding"), ngx_string("") },
     { ngx_string("Keep-Alive"), ngx_string("") },
     { ngx_string("Expect"), ngx_string("") },
     { ngx_string("Upgrade"), ngx_string("") },
@@ -793,6 +801,10 @@ static ngx_http_variable_t  ngx_http_pro
       ngx_http_proxy_internal_body_length_variable, 0,
       NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_NOHASH, 0 },
 
+    { ngx_string("proxy_internal_chunked"), NULL,
+      ngx_http_proxy_internal_chunked_variable, 0,
+      NGX_HTTP_VAR_NOCACHEABLE|NGX_HTTP_VAR_NOHASH, 0 },
+
     { ngx_null_string, NULL, NULL, 0, 0, 0 }
 };
 
@@ -885,10 +897,9 @@ ngx_http_proxy_handler(ngx_http_request_
 
     if (!plcf->upstream.request_buffering
         && plcf->body_values == NULL && plcf->upstream.pass_request_body
-        && !r->headers_in.chunked)
+        && (!r->headers_in.chunked
+            || plcf->http_version == NGX_HTTP_VERSION_11))
     {
-        /* TODO: support chunked when using HTTP/1.1 */
-
         r->request_body_no_buffering = 1;
     }
 
@@ -1210,6 +1221,10 @@ ngx_http_proxy_create_request(ngx_http_r
         ctx->internal_body_length = body_len;
         len += body_len;
 
+    } else if (r->headers_in.chunked && r->reading_body) {
+        ctx->internal_body_length = -1;
+        ctx->internal_chunked = 1;
+
     } else {
         ctx->internal_body_length = r->headers_in.content_length_n;
     }
@@ -1413,6 +1428,11 @@ ngx_http_proxy_create_request(ngx_http_r
 
         u->request_bufs = cl;
 
+        if (ctx->internal_chunked) {
+            u->output.output_filter = ngx_http_proxy_body_output_filter;
+            u->output.filter_ctx = r;
+        }
+
     } else if (plcf->body_values == NULL && plcf->upstream.pass_request_body) {
 
         body = u->request_bufs;
@@ -1475,6 +1495,172 @@ ngx_http_proxy_reinit_request(ngx_http_r
 
 
 static ngx_int_t
+ngx_http_proxy_body_output_filter(void *data, ngx_chain_t *in)
+{
+    ngx_http_request_t  *r = data;
+
+    off_t                  size;
+    u_char                *chunk;
+    ngx_int_t              rc;
+    ngx_buf_t             *b;
+    ngx_chain_t           *out, *cl, *tl, **ll;
+    ngx_http_proxy_ctx_t  *ctx;
+
+    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                   "proxy output filter");
+
+    ctx = ngx_http_get_module_ctx(r, ngx_http_proxy_module);
+
+    if (in == NULL) {
+        out = in;
+        goto out;
+    }
+
+    out = NULL;
+    ll = &out;
+
+    if (!ctx->header_sent) {
+        /* first buffer contains headers, pass it unmodified */
+
+        ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "proxy output header");
+
+        ctx->header_sent = 1;
+
+        tl = ngx_alloc_chain_link(r->pool);
+        if (tl == NULL) {
+            return NGX_ERROR;
+        }
+
+        tl->buf = in->buf;
+        *ll = tl;
+        ll = &tl->next;
+
+        in = in->next;
+
+        if (in == NULL) {
+            tl->next = NULL;
+            goto out;
+        }
+    }
+
+    size = 0;
+    cl = in;
+
+    for ( ;; ) {
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
+                       "proxy output chunk: %d", ngx_buf_size(cl->buf));
+
+        size += ngx_buf_size(cl->buf);
+
+        if (cl->buf->flush
+            || cl->buf->sync
+            || ngx_buf_in_memory(cl->buf)
+            || cl->buf->in_file)
+        {
+            tl = ngx_alloc_chain_link(r->pool);
+            if (tl == NULL) {
+                return NGX_ERROR;
+            }
+
+            tl->buf = cl->buf;
+            *ll = tl;
+            ll = &tl->next;
+        }
+
+        if (cl->next == NULL) {
+            break;
+        }
+
+        cl = cl->next;
+    }
+
+    if (size) {
+        tl = ngx_chain_get_free_buf(r->pool, &ctx->free);
+        if (tl == NULL) {
+            return NGX_ERROR;
+        }
+
+        b = tl->buf;
+        chunk = b->start;
+
+        if (chunk == NULL) {
+            /* the "0000000000000000" is 64-bit hexadecimal string */
+
+            chunk = ngx_palloc(r->pool, sizeof("0000000000000000" CRLF) - 1);
+            if (chunk == NULL) {
+                return NGX_ERROR;
+            }
+
+            b->start = chunk;
+            b->end = chunk + sizeof("0000000000000000" CRLF) - 1;
+        }
+
+        b->tag = (ngx_buf_tag_t) &ngx_http_proxy_body_output_filter;
+        b->memory = 0;
+        b->temporary = 1;
+        b->pos = chunk;
+        b->last = ngx_sprintf(chunk, "%xO" CRLF, size);
+
+        tl->next = out;
+        out = tl;
+    }
+
+    if (cl->buf->last_buf) {
+        tl = ngx_chain_get_free_buf(r->pool, &ctx->free);
+        if (tl == NULL) {
+            return NGX_ERROR;
+        }
+
+        b = tl->buf;
+
+        b->tag = (ngx_buf_tag_t) &ngx_http_proxy_body_output_filter;
+        b->temporary = 0;
+        b->memory = 1;
+        b->last_buf = 1;
+        b->pos = (u_char *) CRLF "0" CRLF CRLF;
+        b->last = b->pos + 7;
+
+        cl->buf->last_buf = 0;
+
+        *ll = tl;
+
+        if (size == 0) {
+            b->pos += 2;
+        }
+
+    } else if (size > 0) {
+        tl = ngx_chain_get_free_buf(r->pool, &ctx->free);
+        if (tl == NULL) {
+            return NGX_ERROR;
+        }
+
+        b = tl->buf;
+
+        b->tag = (ngx_buf_tag_t) &ngx_http_proxy_body_output_filter;
+        b->temporary = 0;
+        b->memory = 1;
+        b->pos = (u_char *) CRLF;
+        b->last = b->pos + 2;
+
+        *ll = tl;
+
+    } else {
+        *ll = NULL;
+    }
+
+out:
+
+    rc = ngx_chain_writer(&r->upstream->writer, out);
+
+    ngx_chain_update_chains(r->pool, &ctx->free, &ctx->busy, &out,
+                            (ngx_buf_tag_t) &ngx_http_proxy_body_output_filter);
+
+    return rc;
+}
+
+
+static ngx_int_t
 ngx_http_proxy_process_status_line(ngx_http_request_t *r)
 {
     size_t                 len;
@@ -2268,6 +2454,30 @@ ngx_http_proxy_internal_body_length_vari
 
 
 static ngx_int_t
+ngx_http_proxy_internal_chunked_variable(ngx_http_request_t *r,
+    ngx_http_variable_value_t *v, uintptr_t data)
+{
+    ngx_http_proxy_ctx_t  *ctx;
+
+    ctx = ngx_http_get_module_ctx(r, ngx_http_proxy_module);
+
+    if (ctx == NULL || !ctx->internal_chunked) {
+        v->not_found = 1;
+        return NGX_OK;
+    }
+
+    v->valid = 1;
+    v->no_cacheable = 0;
+    v->not_found = 0;
+
+    v->data = (u_char *) "chunked";
+    v->len = sizeof("chunked") - 1;
+
+    return NGX_OK;
+}
+
+
+static ngx_int_t
 ngx_http_proxy_rewrite_redirect(ngx_http_request_t *r, ngx_table_elt_t *h,
     size_t prefix)
 {