diff --git a/ext/standard/file.h b/ext/standard/file.h
index 2b2307cab7278..0f3ccd7c27ab3 100644
--- a/ext/standard/file.h
+++ b/ext/standard/file.h
@@ -60,6 +60,12 @@ PHPAPI ssize_t php_fputcsv(php_stream *stream, zval *fields, char delimiter, cha
 #define PHP_FILE_APPEND (1 << 3)
 #define PHP_FILE_NO_DEFAULT_CONTEXT (1 << 4)
 
+#ifndef _WIN32
+#define PHP_TIMEOUT_ULL_MAX ULLONG_MAX
+#else
+#define PHP_TIMEOUT_ULL_MAX UINT64_MAX
+#endif
+
 typedef enum _php_meta_tags_token {
 	TOK_EOF = 0,
 	TOK_OPENTAG,
diff --git a/ext/standard/fsock.c b/ext/standard/fsock.c
index 9e1a53c0ec2a0..0ad0735906ebc 100644
--- a/ext/standard/fsock.c
+++ b/ext/standard/fsock.c
@@ -73,14 +73,27 @@ static void php_fsockopen_stream(INTERNAL_FUNCTION_PARAMETERS, int persistent)
 	}
 
 	/* prepare the timeout value for use */
+	if (timeout != -1.0 && !(timeout >= 0.0 && timeout <= (double) PHP_TIMEOUT_ULL_MAX / 1000000.0)) {
+		if (port > 0) {
+			efree(hostname);
+		}
+
+		if (hashkey) {
+			efree(hashkey);
+		}
+
+		zend_argument_value_error(6, "must be -1 or between 0 and " ZEND_ULONG_FMT, (PHP_TIMEOUT_ULL_MAX / 1000000.0));
+		RETURN_THROWS();
+	} else {
 #ifndef PHP_WIN32
-	conv = (time_t) (timeout * 1000000.0);
-	tv.tv_sec = conv / 1000000;
+		conv = (time_t) (timeout * 1000000.0);
+		tv.tv_sec = conv / 1000000;
 #else
-	conv = (long) (timeout * 1000000.0);
-	tv.tv_sec = conv / 1000000;
+		conv = (long) (timeout * 1000000.0);
+		tv.tv_sec = conv / 1000000;
 #endif
-	tv.tv_usec = conv % 1000000;
+		tv.tv_usec = conv % 1000000;
+	}
 
 	stream = php_stream_xport_create(hostname, hostname_len, REPORT_ERRORS,
 			STREAM_XPORT_CLIENT | STREAM_XPORT_CONNECT, hashkey, &tv, NULL, &errstr, &err);
diff --git a/ext/standard/streamsfuncs.c b/ext/standard/streamsfuncs.c
index 53fa8d33dad6b..7a0e82c7eb5a3 100644
--- a/ext/standard/streamsfuncs.c
+++ b/ext/standard/streamsfuncs.c
@@ -33,13 +33,11 @@
 #ifndef PHP_WIN32
 #define php_select(m, r, w, e, t)	select(m, r, w, e, t)
 typedef unsigned long long php_timeout_ull;
-#define PHP_TIMEOUT_ULL_MAX ULLONG_MAX
 #else
 #include "win32/select.h"
 #include "win32/sockets.h"
 #include "win32/console.h"
 typedef unsigned __int64 php_timeout_ull;
-#define PHP_TIMEOUT_ULL_MAX UINT64_MAX
 #endif
 
 #define GET_CTX_OPT(stream, wrapper, name, val) (PHP_STREAM_CONTEXT(stream) && NULL != (val = php_stream_context_get_option(PHP_STREAM_CONTEXT(stream), wrapper, name)))
diff --git a/ext/standard/tests/streams/gh14780.phpt b/ext/standard/tests/streams/gh14780.phpt
new file mode 100644
index 0000000000000..064e496b17538
--- /dev/null
+++ b/ext/standard/tests/streams/gh14780.phpt
@@ -0,0 +1,38 @@
+--TEST--
+GH-14780: p(f)sockopen overflow on timeout.
+--SKIPIF--
+<?php
+if (PHP_INT_SIZE != 8) die("skip this test is for 64bit platform only");
+?>
+--FILE--
+<?php
+$code = null;
+$err = null;
+try {
+	pfsockopen('udp://127.0.0.1', '63844', $code, $err, (PHP_INT_MAX/100000)+1);
+} catch (\ValueError $e) {
+	echo $e->getMessage() . PHP_EOL;
+}
+try {
+	pfsockopen('udp://127.0.0.1', '63844', $code, $err, (PHP_INT_MIN/100000)-1);
+} catch (\ValueError $e) {
+	echo $e->getMessage() . PHP_EOL;
+}
+var_dump(pfsockopen('udp://127.0.0.1', '63844', $code, $err, -1));
+try {
+	pfsockopen('udp://127.0.0.1', '63844', $code, $err, NAN);
+} catch (\ValueError $e) {
+	echo $e->getMessage() . PHP_EOL;
+}
+try {
+	pfsockopen('udp://127.0.0.1', '63844', $code, $err, INF);
+} catch (\ValueError $e) {
+	echo $e->getMessage();
+}
+?>
+--EXPECTF--
+pfsockopen(): Argument #6 must be -1 or between 0 and %s
+pfsockopen(): Argument #6 must be -1 or between 0 and %s
+resource(%d) of type (persistent stream)
+pfsockopen(): Argument #6 must be -1 or between 0 and %s
+pfsockopen(): Argument #6 must be -1 or between 0 and %s