Index: clang/lib/Format/UnwrappedLineParser.h
===================================================================
--- clang/lib/Format/UnwrappedLineParser.h
+++ clang/lib/Format/UnwrappedLineParser.h
@@ -92,6 +92,7 @@
   void reset();
   void parseFile();
   bool precededByCommentOrPPDirective() const;
+  bool mightFitOnOneLine() const;
   bool parseLevel(bool HasOpeningBrace, bool CanContainBracedList,
                   IfStmtKind *IfKind = nullptr,
                   TokenType NextLBracesType = TT_Unknown);
Index: clang/lib/Format/UnwrappedLineParser.cpp
===================================================================
--- clang/lib/Format/UnwrappedLineParser.cpp
+++ clang/lib/Format/UnwrappedLineParser.cpp
@@ -14,6 +14,7 @@
 
 #include "UnwrappedLineParser.h"
 #include "FormatToken.h"
+#include "TokenAnnotator.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -460,13 +461,56 @@
   return Previous && Previous->is(tok::comment) &&
          (Previous->IsMultiline || Previous->NewlinesBefore > 0);
 }
+
+bool UnwrappedLineParser::mightFitOnOneLine() const {
+  const auto ColumnLimit = Style.ColumnLimit;
+  if (ColumnLimit == 0)
+    return true;
+
+  if (Lines.empty())
+    return true;
+
+  const auto &PreviousLine = Lines.back();
+  const auto &Tokens = PreviousLine.Tokens;
+  assert(!Tokens.empty());
+  const auto *LastToken = Tokens.back().Tok;
+  assert(LastToken);
+  if (!LastToken->isOneOf(tok::semi, tok::comment))
+    return true;
+
+  SmallVector<FormatToken *> SavedTokens;
+  for (const auto &Token : PreviousLine.Tokens) {
+    FormatToken *Tok = new FormatToken;
+    Tok->copyFrom(*Token.Tok);
+    SavedTokens.push_back(Tok);
+  }
+
+  AnnotatedLine Line(PreviousLine);
+  assert(Line.Last == LastToken);
+
+  TokenAnnotator Annotator(Style, Keywords);
+  Annotator.annotate(Line);
+  Annotator.calculateFormattingInformation(Line);
+
+  const int Length = LastToken->TotalLength;
+
+  int I = 0;
+  for (const auto &Token : PreviousLine.Tokens) {
+    const FormatToken *Tok = SavedTokens[I++];
+    Token.Tok->copyFrom(*Tok);
+    delete Tok;
+  }
+
+  return Line.Level * Style.IndentWidth + Length <= ColumnLimit;
+}
+
 /// \brief Parses a level, that is ???.
 /// \param HasOpeningBrace If that level is started by an opening brace.
 /// \param CanContainBracedList If the content can contain (at any level) a
 /// braced list.
 /// \param NextLBracesType The type for left brace found in this level.
 /// \returns true if a simple block, or false otherwise. (A simple block has a
-/// single statement.)
+/// single statement that fits on a single line.)
 bool UnwrappedLineParser::parseLevel(bool HasOpeningBrace,
                                      bool CanContainBracedList,
                                      IfStmtKind *IfKind,
@@ -533,7 +577,9 @@
             precededByCommentOrPPDirective())
           return false;
         const FormatToken *Next = Tokens->peekNextToken();
-        return Next->isNot(tok::comment) || Next->NewlinesBefore > 0;
+        if (Next->is(tok::comment) && Next->NewlinesBefore == 0)
+          return false;
+        return mightFitOnOneLine();
       }
       nextToken();
       addUnwrappedLine();
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -25351,8 +25351,6 @@
                "}",
                Style);
 
-  // FIXME: See https://github.com/llvm/llvm-project/issues/53543.
-#if 0
   Style.ColumnLimit = 65;
 
   verifyFormat("if (condition) {\n"
@@ -25380,9 +25378,6 @@
                "  b = c >= 0 ? d : e;\n"
                "}",
                Style);
-#endif
-
-  Style.ColumnLimit = 20;
 
   verifyFormat("if (a)\n"
                "  b = c > 0 ? d : e;",