diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index 445a406..9477f5e 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -1480,6 +1480,11 @@
     unsigned Length = 0;
     if (!fitsIntoLimit(I->First, Limit, &Length))
       return false;
+
+    // We can never merge stuff if there are trailing line comments.
+    if (I->Last->Type == TT_LineComment)
+      return true;
+
     if (Limit == Length)
       return true; // Couldn't fit a space.
     Limit -= Length + 1; // One space.
@@ -1516,6 +1521,8 @@
     if (!Style.AllowShortIfStatementsOnASingleLine)
       return;
     AnnotatedLine &Line = *I;
+    if (Line.Last->isNot(tok::r_paren))
+      return;
     if (!fitsIntoLimit((I + 1)->First, Limit))
       return;
     if ((I + 1)->First.is(tok::kw_if) || (I + 1)->First.Type == TT_LineComment)
diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index eb00d01..ac61af3 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -145,7 +145,17 @@
   verifyFormat("if (a) return;", getGoogleStyleWithColumns(14));
   verifyFormat("if (a)\n  return;", getGoogleStyleWithColumns(13));
   verifyFormat("if (aaaaaaaaa)\n"
-                     "  return;", getGoogleStyleWithColumns(14));
+               "  return;", getGoogleStyleWithColumns(14));
+  verifyGoogleFormat("if (a)  // Can't merge this\n"
+                     "  f();\n");
+  verifyGoogleFormat("if (a) /* still don't merge */\n"
+                     "  f();");
+  verifyGoogleFormat("if (a) {  // Never merge this\n"
+                     "  f();\n"
+                     "}");
+  verifyGoogleFormat("if (a) { /* Never merge this */\n"
+                     "  f();\n"
+                     "}");
 }
 
 TEST_F(FormatTest, ParseIfElse) {