diff --git a/clang/lib/Format/ContinuationIndenter.h b/clang/lib/Format/ContinuationIndenter.h
--- a/clang/lib/Format/ContinuationIndenter.h
+++ b/clang/lib/Format/ContinuationIndenter.h
@@ -434,7 +434,7 @@
 
   /// A stack keeping track of properties applying to parenthesis
   /// levels.
-  std::vector<ParenState> Stack;
+  SmallVector<ParenState> Stack;
 
   /// Ignore the stack of \c ParenStates for state comparison.
   ///
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -37,7 +37,7 @@
 // Returns the length of everything up to the first possible line break after
 // the ), ], } or > matching \c Tok.
 static unsigned getLengthToMatchingParen(const FormatToken &Tok,
-                                         const std::vector<ParenState> &Stack) {
+                                         const SmallVector<ParenState> &Stack) {
   // Normally whether or not a break before T is possible is calculated and
   // stored in T.CanBreakBefore. Braces, array initializers and text proto
   // messages like `key: < ... >` are an exception: a break is possible
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -2386,7 +2386,7 @@
 
   tooling::Replacements generateFixes() {
     tooling::Replacements Fixes;
-    std::vector<FormatToken *> Tokens;
+    SmallVector<FormatToken *> Tokens;
     std::copy(DeletedTokens.begin(), DeletedTokens.end(),
               std::back_inserter(Tokens));
 
@@ -2580,7 +2580,7 @@
   StringRef Identifier;
   StringRef Text;
   unsigned Offset;
-  std::vector<StringRef> AssociatedCommentLines;
+  SmallVector<StringRef> AssociatedCommentLines;
   bool IsStatic;
 };
 
@@ -2983,7 +2983,7 @@
   llvm::Regex ImportRegex(JavaImportRegexPattern);
   SmallVector<StringRef, 4> Matches;
   SmallVector<JavaImportDirective, 16> ImportsInBlock;
-  std::vector<StringRef> AssociatedCommentLines;
+  SmallVector<StringRef> AssociatedCommentLines;
 
   bool FormattingOff = false;
 
diff --git a/clang/lib/Format/FormatToken.cpp b/clang/lib/Format/FormatToken.cpp
--- a/clang/lib/Format/FormatToken.cpp
+++ b/clang/lib/Format/FormatToken.cpp
@@ -264,7 +264,7 @@
   // We can never place more than ColumnLimit / 3 items in a row (because of the
   // spaces and the comma).
   unsigned MaxItems = Style.ColumnLimit / 3;
-  std::vector<unsigned> MinSizeInColumn;
+  SmallVector<unsigned> MinSizeInColumn;
   MinSizeInColumn.reserve(MaxItems);
   for (unsigned Columns = 1; Columns <= MaxItems; ++Columns) {
     ColumnFormat Format;
diff --git a/clang/lib/Format/Macros.h b/clang/lib/Format/Macros.h
--- a/clang/lib/Format/Macros.h
+++ b/clang/lib/Format/Macros.h
@@ -128,7 +128,7 @@
   const FormatStyle &Style;
   llvm::SpecificBumpPtrAllocator<FormatToken> &Allocator;
   IdentifierTable &IdentTable;
-  std::vector<std::unique_ptr<llvm::MemoryBuffer>> Buffers;
+  SmallVector<std::unique_ptr<llvm::MemoryBuffer>> Buffers;
   llvm::StringMap<Definition> Definitions;
 };
 
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
@@ -1132,7 +1132,7 @@
   typedef std::pair<OrderedPenalty, StateNode *> QueueItem;
 
   /// The BFS queue type.
-  typedef std::priority_queue<QueueItem, std::vector<QueueItem>,
+  typedef std::priority_queue<QueueItem, SmallVector<QueueItem>,
                               std::greater<QueueItem>>
       QueueType;