diff --git a/ext/standard/file.c b/ext/standard/file.c
index 4c31ee0eae661..5c0bf178bbbfd 100644
--- a/ext/standard/file.c
+++ b/ext/standard/file.c
@@ -566,6 +566,11 @@ PHP_FUNCTION(file_get_contents)
 		RETURN_FALSE;
 	}
 
+	/* disabling the read buffer allows doing the whole transfer
+	   in just one read() system call */
+	if (php_stream_is(stream, PHP_STREAM_IS_STDIO))
+		php_stream_set_option(stream, PHP_STREAM_OPTION_READ_BUFFER, PHP_STREAM_BUFFER_NONE, NULL);
+
 	if (offset != 0 && php_stream_seek(stream, offset, ((offset > 0) ? SEEK_SET : SEEK_END)) < 0) {
 		php_error_docref(NULL, E_WARNING, "Failed to seek to position " ZEND_LONG_FMT " in the stream", offset);
 		php_stream_close(stream);
diff --git a/ext/standard/tests/streams/bug54946.phpt b/ext/standard/tests/streams/bug54946.phpt
index 3be2a1367bc15..2e56b8abc5c80 100644
--- a/ext/standard/tests/streams/bug54946.phpt
+++ b/ext/standard/tests/streams/bug54946.phpt
@@ -31,11 +31,6 @@ fclose($stream);
 unlink($filename);
 ?>
 --EXPECTF--
-Notice: stream_get_contents(): Read of 8192 bytes failed with errno=9 Bad file descriptor in %s on line %d
 string(0) ""
-
-Notice: stream_get_contents(): Read of 8192 bytes failed with errno=9 Bad file descriptor in %s on line %d
 string(0) ""
-
-Notice: stream_get_contents(): Read of 8192 bytes failed with errno=9 Bad file descriptor in %s on line %d
 string(0) ""
diff --git a/main/streams/streams.c b/main/streams/streams.c
index 8a7e328007215..f2c599b3f8c2e 100644
--- a/main/streams/streams.c
+++ b/main/streams/streams.c
@@ -706,7 +706,11 @@ PHPAPI ssize_t _php_stream_read(php_stream *stream, char *buf, size_t size)
 			break;
 		}
 
-		if (!stream->readfilters.head && ((stream->flags & PHP_STREAM_FLAG_NO_BUFFER) || stream->chunk_size == 1)) {
+		/* if the read buffer is currently empty, don't buffer
+		 * large reads (larger than chunk_size), because
+		 * buffering would only hurt performance in such an
+		 * edge case */
+		if (!stream->readfilters.head && ((stream->flags & PHP_STREAM_FLAG_NO_BUFFER) || stream->chunk_size == 1 || (stream->writepos == stream->readpos && size >= stream->chunk_size))) {
 			toread = stream->ops->read(stream, buf, size);
 			if (toread < 0) {
 				/* Report an error if the read failed and we did not read any data
@@ -1470,6 +1474,26 @@ PHPAPI zend_string *_php_stream_copy_to_mem(php_stream *src, size_t maxlen, int
 		return ZSTR_EMPTY_ALLOC();
 	}
 
+	if (php_stream_is(src, PHP_STREAM_IS_STDIO) &&
+	    src->readfilters.head == NULL &&
+	    php_stream_stat(src, &ssbuf) == 0 &&
+#ifdef S_ISREG
+	    S_ISREG(ssbuf.sb.st_mode) &&
+#endif
+	    ssbuf.sb.st_size >= 0) {
+		/* optimized code path for unfiltered regular files:
+		 * if we know the exact size, we can allocate the
+		 * right buffer size and issue only one read() system
+		 * call */
+
+		if (ssbuf.sb.st_size <= src->position)
+			return ZSTR_EMPTY_ALLOC();
+
+		const size_t remaining = ssbuf.sb.st_size - src->position;
+		if (remaining < maxlen)
+			maxlen = remaining;
+	}
+
 	if (maxlen == PHP_STREAM_COPY_ALL) {
 		maxlen = 0;
 	}
@@ -1517,7 +1541,7 @@ PHPAPI zend_string *_php_stream_copy_to_mem(php_stream *src, size_t maxlen, int
 	ptr = ZSTR_VAL(result);
 
 	// TODO: Propagate error?
-	while ((ret = php_stream_read(src, ptr, max_len - len)) > 0){
+	while (!php_stream_eof(src) && (ret = php_stream_read(src, ptr, max_len - len)) > 0){
 		len += ret;
 		if (len + min_room >= max_len) {
 			result = zend_string_extend(result, max_len + step, persistent);