diff --git a/src/libs/cplusplus/pp-engine.cpp b/src/libs/cplusplus/pp-engine.cpp
index 9c86b7e35d2f748513efb1bfd6f4c7e594d9bb7d..21440bc86c13121c1579814992bf3da779938977 100644
--- a/src/libs/cplusplus/pp-engine.cpp
+++ b/src/libs/cplusplus/pp-engine.cpp
@@ -2039,6 +2039,15 @@ bool Preprocessor::atStartOfOutputLine() const
 void Preprocessor::maybeStartOutputLine()
 {
     QByteArray &buffer = currentOutputBuffer();
-    if (!buffer.isEmpty() && !buffer.endsWith('\n'))
+    if (buffer.isEmpty())
+        return;
+    if (!buffer.endsWith('\n'))
+        buffer.append('\n');
+    // If previous line ends with \ (possibly followed by whitespace), add another \n
+    const char *start = buffer.constData();
+    const char *ch = start + buffer.length() - 2;
+    while (ch > start && (*ch != '\n') && std::isspace(*ch))
+        --ch;
+    if (*ch == '\\')
         buffer.append('\n');
 }
diff --git a/tests/auto/cplusplus/preprocessor/tst_preprocessor.cpp b/tests/auto/cplusplus/preprocessor/tst_preprocessor.cpp
index b262db3b40fcf6ac5c182010c5beb597f2f42429..ca3460335d24070b9fa1b8711108cc27c79cfc13 100644
--- a/tests/auto/cplusplus/preprocessor/tst_preprocessor.cpp
+++ b/tests/auto/cplusplus/preprocessor/tst_preprocessor.cpp
@@ -1453,6 +1453,31 @@ void tst_Preprocessor::comments_within_data()
             "\n"
             "int foo = 4;"
     );
+
+    QTest::newRow("joined_unterminated") << _(
+            "// comment \\\n"
+            "\n"
+            "\n"
+            "\n"
+            "\n"
+            "\n"
+            "\n"
+            "\n"
+            "\n"
+            "\n"
+            "\n"
+            "int foo = 4;"
+        ) << _(
+            "# 1 \"<stdin>\"\n"
+            "# 12 \"<stdin>\"\n"
+            "int foo = 4;"
+        ) << _(
+            "# 1 \"<stdin>\"\n"
+            "// comment \\\n"
+            "\n"
+            "# 12 \"<stdin>\"\n"
+            "int foo = 4;"
+    );
 }
 
 void tst_Preprocessor::comments_before_args()