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
@@ -411,7 +411,7 @@
                  ? tryMergeSimpleControlStatement(I, E, Limit)
                  : 0;
     }
-    if (TheLine->First->isOneOf(tok::kw_for, tok::kw_while)) {
+    if (TheLine->First->isOneOf(tok::kw_for, tok::kw_while, tok::kw_do)) {
       return Style.AllowShortLoopsOnASingleLine
                  ? tryMergeSimpleControlStatement(I, E, Limit)
                  : 0;
@@ -514,7 +514,10 @@
       return 0;
     Limit = limitConsideringMacros(I + 1, E, Limit);
     AnnotatedLine &Line = **I;
-    if (Line.Last->isNot(tok::r_paren))
+    if (!Line.First->is(tok::kw_do) && 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))
       return 0;
     if (1 + I[1]->Last->TotalLength > Limit)
       return 0;
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
@@ -556,6 +556,30 @@
   verifyFormat("for (;;) /* still don't merge */\n"
                "  continue;",
                AllowsMergedLoops);
+  verifyFormat("do a++;\n"
+               "while (true);",
+               AllowsMergedLoops);
+  verifyFormat("do /* Don't merge */\n"
+               "  a++;\n"
+               "while (true);",
+               AllowsMergedLoops);
+  verifyFormat("do // Don't merge\n"
+               "  a++;\n"
+               "while (true);",
+               AllowsMergedLoops);
+  verifyFormat("do\n"
+               "  // Don't merge\n"
+               "  a++;\n"
+               "while (true);",
+               AllowsMergedLoops);
+  // Without braces labels are interpreted differently.
+  verifyFormat("{\n"
+               "  do\n"
+               "  label:\n"
+               "    a++;\n"
+               "  while (true);\n"
+               "}",
+               AllowsMergedLoops);
 }
 
 TEST_F(FormatTest, FormatShortBracedStatements) {