Index: lib/Format/UnwrappedLineFormatter.cpp
===================================================================
--- lib/Format/UnwrappedLineFormatter.cpp	(revision 311154)
+++ lib/Format/UnwrappedLineFormatter.cpp	(working copy)
@@ -283,6 +283,21 @@
         TheLine->First != TheLine->Last) {
       return MergeShortFunctions ? tryMergeSimpleBlock(I, E, Limit) : 0;
     }
+    if (TheLine->Last->is(tok::l_brace) &&
+        TheLine->First != TheLine->Last &&
+        TheLine->First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_for)) { 
+      return Style.AllowShortBlocksOnASingleLine ? tryMergeSimpleBlock(I, E, Limit) : 0;
+    }
+    if (I[1]->First->is(tok::l_brace) && 
+        TheLine->First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_for)) { 
+      return Style.BraceWrapping.AfterControlStatement ? tryMergeSimpleBlock(I, E, Limit) : 0;
+    }
+    if (TheLine->First->is(tok::l_brace) &&
+       (TheLine->First == TheLine->Last) &&
+       (I != AnnotatedLines.begin()) &&
+       (I[-1]->First->isOneOf(tok::kw_if, tok::kw_while, tok::kw_for))) { 
+      return Style.AllowShortBlocksOnASingleLine ? tryMergeSimpleBlock(I-1, E, Limit) : 0;
+    }
     if (TheLine->Last->is(tok::l_brace)) {
       return !Style.BraceWrapping.AfterFunction
                  ? tryMergeSimpleBlock(I, E, Limit)
@@ -459,53 +474,74 @@
                               Keywords.kw___except, tok::kw___finally))
         return 0;
     }
+    
+    if (Line.Last->is(tok::l_brace)) {
+      FormatToken *Tok = I[1]->First;
+      if (Tok->is(tok::r_brace) && !Tok->MustBreakBefore &&
+          (Tok->getNextNonComment() == nullptr ||
+          Tok->getNextNonComment()->is(tok::semi))) {
+        // We merge empty blocks even if the line exceeds the column limit.
+        Tok->SpacesRequiredBefore = 0;
+        Tok->CanBreakBefore = true;
+        return 1;
+      } else if (Limit != 0 && !Line.startsWith(tok::kw_namespace) &&
+                 !startsExternCBlock(Line)) {
+        // We don't merge short records.
+        FormatToken *RecordTok =
+            Line.First->is(tok::kw_typedef) ? Line.First->Next : Line.First;
+        if (RecordTok &&
+            RecordTok->isOneOf(tok::kw_class, tok::kw_union, tok::kw_struct,
+                               Keywords.kw_interface))
+          return 0;
 
-    FormatToken *Tok = I[1]->First;
-    if (Tok->is(tok::r_brace) && !Tok->MustBreakBefore &&
-        (Tok->getNextNonComment() == nullptr ||
-         Tok->getNextNonComment()->is(tok::semi))) {
-      // We merge empty blocks even if the line exceeds the column limit.
-      Tok->SpacesRequiredBefore = 0;
-      Tok->CanBreakBefore = true;
-      return 1;
-    } else if (Limit != 0 && !Line.startsWith(tok::kw_namespace) &&
-               !startsExternCBlock(Line)) {
-      // We don't merge short records.
-      FormatToken *RecordTok =
-          Line.First->is(tok::kw_typedef) ? Line.First->Next : Line.First;
-      if (RecordTok &&
-          RecordTok->isOneOf(tok::kw_class, tok::kw_union, tok::kw_struct,
-                             Keywords.kw_interface))
-        return 0;
+        // Check that we still have three lines and they fit into the limit.
+        if (I + 2 == E || I[2]->Type == LT_Invalid)
+          return 0;
+        Limit = limitConsideringMacros(I + 2, E, Limit);
 
-      // Check that we still have three lines and they fit into the limit.
-      if (I + 2 == E || I[2]->Type == LT_Invalid)
-        return 0;
-      Limit = limitConsideringMacros(I + 2, E, Limit);
+        if (!nextTwoLinesFitInto(I, Limit))
+          return 0;
 
-      if (!nextTwoLinesFitInto(I, Limit))
-        return 0;
+        // Second, check that the next line does not contain any braces - if it
+        // does, readability declines when putting it into a single line.
+        if (I[1]->Last->is(TT_LineComment))
+          return 0;
+        do {
+          if (Tok->is(tok::l_brace) && Tok->BlockKind != BK_BracedInit)
+            return 0;
+          Tok = Tok->Next;
+        } while (Tok);
 
-      // Second, check that the next line does not contain any braces - if it
-      // does, readability declines when putting it into a single line.
-      if (I[1]->Last->is(TT_LineComment))
-        return 0;
-      do {
-        if (Tok->is(tok::l_brace) && Tok->BlockKind != BK_BracedInit)
+        // Last, check that the third line starts with a closing brace.
+        Tok = I[2]->First;
+        if (Tok->isNot(tok::r_brace))
           return 0;
-        Tok = Tok->Next;
-      } while (Tok);
 
-      // Last, check that the third line starts with a closing brace.
-      Tok = I[2]->First;
-      if (Tok->isNot(tok::r_brace))
+        // Don't merge "if (a) { .. } else {".
+        if (Tok->Next && Tok->Next->is(tok::kw_else))
+          return 0;
+
+        return 2;
+      }
+    } else if (I[1]->First->is(tok::l_brace)) {
+      if (I[1]->Last->is(TT_LineComment))
         return 0;
 
-      // Don't merge "if (a) { .. } else {".
-      if (Tok->Next && Tok->Next->is(tok::kw_else))
+      // Check for Limit <= 2 to account for the " {".
+      if (Limit <= 2 || (Style.ColumnLimit == 0 && containsMustBreak(*I)))
         return 0;
-
-      return 2;
+      Limit -= 2;
+      unsigned MergedLines = 0;
+      if ((Style.AllowShortBlocksOnASingleLine ||
+          (I[1]->First == I[1]->Last && I + 2 != E &&
+          I[2]->First->is(tok::r_brace)))) {
+      MergedLines = tryMergeSimpleBlock(I + 1, E, Limit);
+      // If we managed to merge the block, count the statement header, which is
+      // on a separate line.
+      if (MergedLines > 0)
+        ++MergedLines;
+      }
+      return MergedLines;
     }
     return 0;
   }