diff --git a/clang/lib/Format/UnwrappedLineFormatter.cpp b/clang/lib/Format/UnwrappedLineFormatter.cpp
--- a/clang/lib/Format/UnwrappedLineFormatter.cpp
+++ b/clang/lib/Format/UnwrappedLineFormatter.cpp
@@ -421,7 +421,13 @@
       }
       return MergedLines;
     }
-    if (TheLine->First->is(tok::kw_if)) {
+    bool IsElseLine =
+        TheLine->First->is(tok::kw_else) ||
+        (TheLine->First->is(tok::r_brace) && TheLine->First->Next &&
+         TheLine->First->Next->is(tok::kw_else));
+    if (TheLine->First->is(tok::kw_if) ||
+        (IsElseLine && (Style.AllowShortIfStatementsOnASingleLine ==
+                        FormatStyle::SIS_Always))) {
       return Style.AllowShortIfStatementsOnASingleLine
                  ? tryMergeSimpleControlStatement(I, E, Limit)
                  : 0;
@@ -471,7 +477,8 @@
       return 0;
     Limit = limitConsideringMacros(I + 1, E, Limit);
     AnnotatedLine &Line = **I;
-    if (!Line.First->is(tok::kw_do) && Line.Last->isNot(tok::r_paren))
+    if (!Line.First->is(tok::kw_do) && !Line.First->is(tok::kw_else) &&
+        !Line.Last->is(tok::kw_else) && Line.Last->isNot(tok::r_paren))
       return 0;
     // Only merge do while if do is the only statement on the line.
     if (Line.First->is(tok::kw_do) && !Line.Last->is(tok::kw_do))
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -510,6 +510,60 @@
 
   AllowsMergedIf.ColumnLimit = 13;
   verifyFormat("if (a)\n  return;", AllowsMergedIf);
+
+  FormatStyle AllowsMergedIfElse = getLLVMStyle();
+  AllowsMergedIfElse.AllowShortIfStatementsOnASingleLine =
+      FormatStyle::SIS_Always;
+  verifyFormat("if (a)\n"
+               "  // comment\n"
+               "  f();\n"
+               "else\n"
+               "  // comment\n"
+               "  f();",
+               AllowsMergedIfElse);
+  verifyFormat("{\n"
+               "  if (a)\n"
+               "  label:\n"
+               "    f();\n"
+               "  else\n"
+               "  label:\n"
+               "    f();\n"
+               "}",
+               AllowsMergedIfElse);
+  // Hum?
+  verifyFormat("if (a)\n"
+               "  ;\n"
+               "else\n"
+               "  ;",
+               AllowsMergedIfElse);
+  verifyFormat("if (a) {\n"
+               "} else {\n"
+               "}",
+               AllowsMergedIfElse);
+  verifyFormat("if (a) return;\n"
+               "else if (b) return;\n"
+               "else return;",
+               AllowsMergedIfElse);
+  verifyFormat("if (a) {\n"
+               "} else return;",
+               AllowsMergedIfElse);
+  verifyFormat("if (a) {\n"
+               "} else if (b) return;\n"
+               "else return;",
+               AllowsMergedIfElse);
+  verifyFormat("if (a) return;\n"
+               "else if (b) {\n"
+               "} else return;",
+               AllowsMergedIfElse);
+  verifyFormat("if (a)\n"
+               "  if (b) return;\n"
+               "  else return;",
+               AllowsMergedIfElse);
+  verifyFormat("if constexpr (a)\n"
+               "  if constexpr (b) return;\n"
+               "  else if constexpr (c) return;\n"
+               "  else return;",
+               AllowsMergedIfElse);
 }
 
 TEST_F(FormatTest, FormatIfWithoutCompoundStatementButElseWith) {