diff --git a/clang-tools-extra/clangd/AST.cpp b/clang-tools-extra/clangd/AST.cpp
--- a/clang-tools-extra/clangd/AST.cpp
+++ b/clang-tools-extra/clangd/AST.cpp
@@ -258,7 +258,7 @@
       // TemplateArgumentTypeLocs, they only have TemplateArgumentTypes. So we
       // create a new argument location list from TypeSourceInfo.
       auto STL = TSI->getTypeLoc().getAs<TemplateSpecializationTypeLoc>();
-      llvm::SmallVector<TemplateArgumentLoc, 8> ArgLocs;
+      llvm::SmallVector<TemplateArgumentLoc> ArgLocs;
       ArgLocs.reserve(STL.getNumArgs());
       for (unsigned I = 0; I < STL.getNumArgs(); ++I)
         ArgLocs.push_back(STL.getArgLoc(I));
diff --git a/clang-tools-extra/clangd/CompileCommands.h b/clang-tools-extra/clangd/CompileCommands.h
--- a/clang-tools-extra/clangd/CompileCommands.h
+++ b/clang-tools-extra/clangd/CompileCommands.h
@@ -92,7 +92,7 @@
   static llvm::ArrayRef<Rule> rulesFor(llvm::StringRef Arg);
   const Rule *matchingRule(llvm::StringRef Arg, unsigned Mode,
                            unsigned &ArgCount) const;
-  llvm::SmallVector<Rule, 4> Rules;
+  llvm::SmallVector<Rule> Rules;
   std::deque<std::string> Storage; // Store strings not found in option table.
 };
 
diff --git a/clang-tools-extra/clangd/CompileCommands.cpp b/clang-tools-extra/clangd/CompileCommands.cpp
--- a/clang-tools-extra/clangd/CompileCommands.cpp
+++ b/clang-tools-extra/clangd/CompileCommands.cpp
@@ -367,7 +367,7 @@
     for (unsigned ID = 1 /*Skip INVALID */; ID < DriverID::LastOption; ++ID) {
       if (PrevAlias[ID] || ID == DriverID::OPT_Xclang)
         continue; // Not canonical, or specially handled.
-      llvm::SmallVector<Rule, 8> Rules;
+      llvm::SmallVector<Rule> Rules;
       // Iterate over each alias, to add rules for parsing it.
       for (unsigned A = ID; A != DriverID::OPT_INVALID; A = NextAlias[A]) {
         if (Prefixes[A] == nullptr) // option groups.
diff --git a/clang-tools-extra/clangd/ConfigCompile.cpp b/clang-tools-extra/clangd/ConfigCompile.cpp
--- a/clang-tools-extra/clangd/ConfigCompile.cpp
+++ b/clang-tools-extra/clangd/ConfigCompile.cpp
@@ -137,7 +137,7 @@
     llvm::StringRef EnumName;
     const Located<std::string> &Input;
     llvm::Optional<T> Result;
-    llvm::SmallVector<llvm::StringLiteral, 8> ValidValues;
+    llvm::SmallVector<llvm::StringLiteral> ValidValues;
 
   public:
     EnumSwitch(llvm::StringRef EnumName, const Located<std::string> &In,
diff --git a/clang-tools-extra/clangd/ConfigProvider.cpp b/clang-tools-extra/clangd/ConfigProvider.cpp
--- a/clang-tools-extra/clangd/ConfigProvider.cpp
+++ b/clang-tools-extra/clangd/ConfigProvider.cpp
@@ -97,7 +97,7 @@
 
       // Compute absolute paths to all ancestors (substrings of P.Path).
       llvm::StringRef Parent = path::parent_path(P.Path);
-      llvm::SmallVector<llvm::StringRef, 8> Ancestors;
+      llvm::SmallVector<llvm::StringRef> Ancestors;
       for (auto I = path::begin(Parent, path::Style::posix),
                 E = path::end(Parent);
            I != E; ++I) {
@@ -108,7 +108,7 @@
         Ancestors.emplace_back(Parent.begin(), I->end() - Parent.begin());
       }
       // Ensure corresponding cache entries exist in the map.
-      llvm::SmallVector<FileConfigCache *, 8> Caches;
+      llvm::SmallVector<FileConfigCache *> Caches;
       {
         std::lock_guard<std::mutex> Lock(Mu);
         for (llvm::StringRef Ancestor : Ancestors) {
diff --git a/clang-tools-extra/clangd/FileDistance.cpp b/clang-tools-extra/clangd/FileDistance.cpp
--- a/clang-tools-extra/clangd/FileDistance.cpp
+++ b/clang-tools-extra/clangd/FileDistance.cpp
@@ -58,8 +58,7 @@
 FileDistance::FileDistance(llvm::StringMap<SourceParams> Sources,
                            const FileDistanceOptions &Opts)
     : Opts(Opts) {
-  llvm::DenseMap<llvm::hash_code, llvm::SmallVector<llvm::hash_code, 4>>
-      DownEdges;
+  llvm::DenseMap<llvm::hash_code, llvm::SmallVector<llvm::hash_code>> DownEdges;
   // Compute the best distance following only up edges.
   // Keep track of down edges, in case we can use them to improve on this.
   for (const auto &S : Sources) {
@@ -118,7 +117,7 @@
 unsigned FileDistance::distance(llvm::StringRef Path) {
   auto Canonical = canonicalize(Path);
   unsigned Cost = Unreachable;
-  llvm::SmallVector<llvm::hash_code, 16> Ancestors;
+  llvm::SmallVector<llvm::hash_code> Ancestors;
   // Walk up ancestors until we find a path we know the distance for.
   for (llvm::StringRef Rest = Canonical; !Rest.empty();
        Rest = parent_path(Rest, llvm::sys::path::Style::posix)) {
@@ -177,7 +176,7 @@
 }
 
 static std::pair<std::string, int> scopeToPath(llvm::StringRef Scope) {
-  llvm::SmallVector<llvm::StringRef, 4> Split;
+  llvm::SmallVector<llvm::StringRef> Split;
   Scope.split(Split, "::", /*MaxSplit=*/-1, /*KeepEmpty=*/false);
   return {"/" + llvm::join(Split, "/"), Split.size()};
 }
diff --git a/clang-tools-extra/clangd/FindTarget.cpp b/clang-tools-extra/clangd/FindTarget.cpp
--- a/clang-tools-extra/clangd/FindTarget.cpp
+++ b/clang-tools-extra/clangd/FindTarget.cpp
@@ -750,9 +750,9 @@
 }
 
 namespace {
-llvm::SmallVector<ReferenceLoc, 2> refInDecl(const Decl *D) {
+llvm::SmallVector<ReferenceLoc> refInDecl(const Decl *D) {
   struct Visitor : ConstDeclVisitor<Visitor> {
-    llvm::SmallVector<ReferenceLoc, 2> Refs;
+    llvm::SmallVector<ReferenceLoc> Refs;
 
     void VisitUsingDirectiveDecl(const UsingDirectiveDecl *D) {
       // We want to keep it as non-declaration references, as the
@@ -819,10 +819,10 @@
   return V.Refs;
 }
 
-llvm::SmallVector<ReferenceLoc, 2> refInStmt(const Stmt *S) {
+llvm::SmallVector<ReferenceLoc> refInStmt(const Stmt *S) {
   struct Visitor : ConstStmtVisitor<Visitor> {
     // FIXME: handle more complicated cases: more ObjC, designated initializers.
-    llvm::SmallVector<ReferenceLoc, 2> Refs;
+    llvm::SmallVector<ReferenceLoc> Refs;
 
     void VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E) {
       Refs.push_back(ReferenceLoc{E->getNestedNameSpecifierLoc(),
@@ -920,7 +920,7 @@
   return V.Refs;
 }
 
-llvm::SmallVector<ReferenceLoc, 2> refInTypeLoc(TypeLoc L) {
+llvm::SmallVector<ReferenceLoc> refInTypeLoc(TypeLoc L) {
   struct Visitor : TypeLocVisitor<Visitor> {
     llvm::Optional<ReferenceLoc> Ref;
 
@@ -1114,7 +1114,7 @@
   ///     be references. However, declarations can have references inside them,
   ///     e.g. 'namespace foo = std' references namespace 'std' and this
   ///     function will return the corresponding reference.
-  llvm::SmallVector<ReferenceLoc, 2> explicitReference(DynTypedNode N) {
+  llvm::SmallVector<ReferenceLoc> explicitReference(DynTypedNode N) {
     if (auto *D = N.get<Decl>())
       return refInDecl(D);
     if (auto *S = N.get<Stmt>())
diff --git a/clang-tools-extra/clangd/Headers.h b/clang-tools-extra/clangd/Headers.h
--- a/clang-tools-extra/clangd/Headers.h
+++ b/clang-tools-extra/clangd/Headers.h
@@ -136,7 +136,7 @@
   unsigned fileIndex(llvm::StringRef Name);
   llvm::StringMap<unsigned> NameToIndex; // Values are file indexes.
   // Maps a file's index to that of the files it includes.
-  llvm::DenseMap<unsigned, SmallVector<unsigned, 8>> IncludeChildren;
+  llvm::DenseMap<unsigned, SmallVector<unsigned>> IncludeChildren;
 };
 
 /// Returns a PPCallback that visits all inclusions in the main file.
diff --git a/clang-tools-extra/clangd/QueryDriverDatabase.cpp b/clang-tools-extra/clangd/QueryDriverDatabase.cpp
--- a/clang-tools-extra/clangd/QueryDriverDatabase.cpp
+++ b/clang-tools-extra/clangd/QueryDriverDatabase.cpp
@@ -79,7 +79,7 @@
   const char SIS[] = "#include <...> search starts here:";
   const char SIE[] = "End of search list.";
   const char TS[] = "Target: ";
-  llvm::SmallVector<llvm::StringRef, 8> Lines;
+  llvm::SmallVector<llvm::StringRef> Lines;
   Output.split(Lines, '\n', /*MaxSplit=*/-1, /*KeepEmpty=*/false);
 
   enum {
@@ -171,8 +171,8 @@
   llvm::Optional<llvm::StringRef> Redirects[] = {
       {""}, {""}, llvm::StringRef(StdErrPath)};
 
-  llvm::SmallVector<llvm::StringRef, 12> Args = {Driver, "-E", "-x",
-                                                 Lang,   "-",  "-v"};
+  llvm::SmallVector<llvm::StringRef> Args = {Driver, "-E", "-x",
+                                             Lang,   "-",  "-v"};
 
   // These flags will be preserved
   const llvm::StringRef FlagsToPreserve[] = {
diff --git a/clang-tools-extra/clangd/Selection.h b/clang-tools-extra/clangd/Selection.h
--- a/clang-tools-extra/clangd/Selection.h
+++ b/clang-tools-extra/clangd/Selection.h
@@ -123,7 +123,7 @@
     // The parent within the selection tree. nullptr for TranslationUnitDecl.
     Node *Parent;
     // Direct children within the selection tree.
-    llvm::SmallVector<const Node *, 8> Children;
+    llvm::SmallVector<const Node *> Children;
     // The corresponding node from the full AST.
     ast_type_traits::DynTypedNode ASTNode;
     // The extent to which this node is covered by the selection.
diff --git a/clang-tools-extra/clangd/Selection.cpp b/clang-tools-extra/clangd/Selection.cpp
--- a/clang-tools-extra/clangd/Selection.cpp
+++ b/clang-tools-extra/clangd/Selection.cpp
@@ -83,8 +83,8 @@
   // Removes the elements of Claim from the set, modifying or removing ranges
   // that overlap it.
   // Returns the continuous subranges of Claim that were actually removed.
-  llvm::SmallVector<llvm::ArrayRef<T>, 4> erase(llvm::ArrayRef<T> Claim) {
-    llvm::SmallVector<llvm::ArrayRef<T>, 4> Out;
+  llvm::SmallVector<llvm::ArrayRef<T>> erase(llvm::ArrayRef<T> Claim) {
+    llvm::SmallVector<llvm::ArrayRef<T>> Out;
     if (Claim.empty())
       return Out;
 
diff --git a/clang-tools-extra/clangd/SemanticHighlighting.cpp b/clang-tools-extra/clangd/SemanticHighlighting.cpp
--- a/clang-tools-extra/clangd/SemanticHighlighting.cpp
+++ b/clang-tools-extra/clangd/SemanticHighlighting.cpp
@@ -605,7 +605,7 @@
   std::vector<TheiaSemanticHighlightingInformation> Lines;
   Lines.reserve(Tokens.size());
   for (const auto &Line : Tokens) {
-    llvm::SmallVector<char, 128> LineByteTokens;
+    llvm::SmallVector<char> LineByteTokens;
     llvm::raw_svector_ostream OS(LineByteTokens);
     for (const auto &Token : Line.Tokens) {
       // Writes the token to LineByteTokens in the byte format specified by the
diff --git a/clang-tools-extra/clangd/SourceCode.cpp b/clang-tools-extra/clangd/SourceCode.cpp
--- a/clang-tools-extra/clangd/SourceCode.cpp
+++ b/clang-tools-extra/clangd/SourceCode.cpp
@@ -779,8 +779,8 @@
 }
 
 // Returns the prefix namespaces of NS: {"" ... NS}.
-llvm::SmallVector<llvm::StringRef, 8> ancestorNamespaces(llvm::StringRef NS) {
-  llvm::SmallVector<llvm::StringRef, 8> Results;
+llvm::SmallVector<llvm::StringRef> ancestorNamespaces(llvm::StringRef NS) {
+  llvm::SmallVector<llvm::StringRef> Results;
   Results.push_back(NS.take_front(0));
   NS.split(Results, "::", /*MaxSplit=*/-1, /*KeepEmpty=*/false);
   for (llvm::StringRef &R : Results)
diff --git a/clang-tools-extra/clangd/TUScheduler.cpp b/clang-tools-extra/clangd/TUScheduler.cpp
--- a/clang-tools-extra/clangd/TUScheduler.cpp
+++ b/clang-tools-extra/clangd/TUScheduler.cpp
@@ -477,7 +477,7 @@
   /// thread are not locked, as it's the only writer.
   ParseInputs FileInputs; /* GUARDED_BY(Mutex) */
   /// Times of recent AST rebuilds, used for UpdateDebounce computation.
-  llvm::SmallVector<DebouncePolicy::clock::duration, 8>
+  llvm::SmallVector<DebouncePolicy::clock::duration>
       RebuildTimes; /* GUARDED_BY(Mutex) */
   /// Set to true to signal run() to finish processing.
   bool Done;                              /* GUARDED_BY(Mutex) */
diff --git a/clang-tools-extra/clangd/TidyProvider.cpp b/clang-tools-extra/clangd/TidyProvider.cpp
--- a/clang-tools-extra/clangd/TidyProvider.cpp
+++ b/clang-tools-extra/clangd/TidyProvider.cpp
@@ -81,7 +81,7 @@
     // Compute absolute paths to all ancestors (substrings of P.Path).
     // Ensure cache entries for each ancestor exist in the map.
     llvm::StringRef Parent = path::parent_path(AbsPath);
-    llvm::SmallVector<DotClangTidyCache *, 8> Caches;
+    llvm::SmallVector<DotClangTidyCache *> Caches;
     {
       std::lock_guard<std::mutex> Lock(Mu);
       for (auto I = path::begin(Parent, path::Style::posix),
@@ -105,7 +105,7 @@
     // This will take a (per-file) lock for each file that actually exists.
     std::chrono::steady_clock::time_point FreshTime =
         std::chrono::steady_clock::now() - MaxStaleness;
-    llvm::SmallVector<std::shared_ptr<const tidy::ClangTidyOptions>, 4>
+    llvm::SmallVector<std::shared_ptr<const tidy::ClangTidyOptions>>
         OptionStack;
     for (const DotClangTidyCache *Cache : Caches)
       if (auto Config = Cache->get(FS, FreshTime)) {
diff --git a/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp b/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
--- a/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
+++ b/clang-tools-extra/clangd/index/dex/dexp/Dexp.cpp
@@ -153,7 +153,7 @@
     Request.Limit = Limit;
     Request.Query = Query;
     if (Scopes.getNumOccurrences() > 0) {
-      llvm::SmallVector<llvm::StringRef, 8> Scopes;
+      llvm::SmallVector<llvm::StringRef> Scopes;
       llvm::StringRef(this->Scopes).split(Scopes, ',');
       Request.Scopes = {Scopes.begin(), Scopes.end()};
     }
@@ -339,7 +339,7 @@
 bool runCommand(std::string Request, const SymbolIndex &Index) {
   // Split on spaces and add required null-termination.
   std::replace(Request.begin(), Request.end(), ' ', '\0');
-  llvm::SmallVector<llvm::StringRef, 8> Args;
+  llvm::SmallVector<llvm::StringRef> Args;
   llvm::StringRef(Request).split(Args, '\0', /*MaxSplit=*/-1,
                                  /*KeepEmpty=*/false);
   if (Args.empty())
@@ -351,7 +351,7 @@
     llvm::outs() << "Get detailed command help with e.g. `find -help`.\n";
     return true;
   }
-  llvm::SmallVector<const char *, 8> FakeArgv;
+  llvm::SmallVector<const char *> FakeArgv;
   for (llvm::StringRef S : Args)
     FakeArgv.push_back(S.data()); // Terminated by separator or end of string.
 
diff --git a/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp b/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
--- a/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/DefineInline.cpp
@@ -480,7 +480,7 @@
     const tooling::Replacement DeleteFuncBody(SM, DefRange->getBegin(),
                                               SourceLen, "");
 
-    llvm::SmallVector<std::pair<std::string, Edit>, 2> Edits;
+    llvm::SmallVector<std::pair<std::string, Edit>> Edits;
     // Edit for Target.
     auto FE = Effect::fileEdit(SM, SM.getFileID(*Semicolon),
                                std::move(TargetFileReplacements));
diff --git a/clang-tools-extra/clangd/refactor/tweaks/ExtractVariable.cpp b/clang-tools-extra/clangd/refactor/tweaks/ExtractVariable.cpp
--- a/clang-tools-extra/clangd/refactor/tweaks/ExtractVariable.cpp
+++ b/clang-tools-extra/clangd/refactor/tweaks/ExtractVariable.cpp
@@ -202,7 +202,7 @@
 struct ParsedBinaryOperator {
   BinaryOperatorKind Kind;
   SourceLocation ExprLoc;
-  llvm::SmallVector<const SelectionTree::Node*, 8> SelectedOperands;
+  llvm::SmallVector<const SelectionTree::Node *> SelectedOperands;
 
   // If N is a binary operator, populate this and return true.
   bool parse(const SelectionTree::Node &N) {
diff --git a/clang-tools-extra/clangd/support/Markup.cpp b/clang-tools-extra/clangd/support/Markup.cpp
--- a/clang-tools-extra/clangd/support/Markup.cpp
+++ b/clang-tools-extra/clangd/support/Markup.cpp
@@ -215,7 +215,7 @@
 
 // Trims the input and concatenates whitespace blocks into a single ` `.
 std::string canonicalizeSpaces(llvm::StringRef Input) {
-  llvm::SmallVector<llvm::StringRef, 4> Words;
+  llvm::SmallVector<llvm::StringRef> Words;
   llvm::SplitString(Input, Words);
   return llvm::join(Words, " ");
 }
diff --git a/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp b/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp
--- a/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CompileCommandsTests.cpp
@@ -208,7 +208,7 @@
 }
 
 static std::string strip(llvm::StringRef Arg, llvm::StringRef Argv) {
-  llvm::SmallVector<llvm::StringRef, 8> Parts;
+  llvm::SmallVector<llvm::StringRef> Parts;
   llvm::SplitString(Argv, Parts);
   std::vector<std::string> Args = {Parts.begin(), Parts.end()};
   ArgStripper S;
diff --git a/clang-tools-extra/clangd/unittests/TestIndex.cpp b/clang-tools-extra/clangd/unittests/TestIndex.cpp
--- a/clang-tools-extra/clangd/unittests/TestIndex.cpp
+++ b/clang-tools-extra/clangd/unittests/TestIndex.cpp
@@ -29,7 +29,7 @@
 
 static std::string replace(llvm::StringRef Haystack, llvm::StringRef Needle,
                            llvm::StringRef Repl) {
-  llvm::SmallVector<llvm::StringRef, 8> Parts;
+  llvm::SmallVector<llvm::StringRef> Parts;
   Haystack.split(Parts, Needle);
   return llvm::join(Parts, Repl);
 }
diff --git a/clang-tools-extra/clangd/unittests/TestTU.cpp b/clang-tools-extra/clangd/unittests/TestTU.cpp
--- a/clang-tools-extra/clangd/unittests/TestTU.cpp
+++ b/clang-tools-extra/clangd/unittests/TestTU.cpp
@@ -187,7 +187,7 @@
 }
 
 const NamedDecl &findDecl(ParsedAST &AST, llvm::StringRef QName) {
-  llvm::SmallVector<llvm::StringRef, 4> Components;
+  llvm::SmallVector<llvm::StringRef> Components;
   QName.split(Components, "::");
 
   auto &Ctx = AST.getASTContext();
diff --git a/clang-tools-extra/clangd/unittests/support/TraceTests.cpp b/clang-tools-extra/clangd/unittests/support/TraceTests.cpp
--- a/clang-tools-extra/clangd/unittests/support/TraceTests.cpp
+++ b/clang-tools-extra/clangd/unittests/support/TraceTests.cpp
@@ -154,7 +154,7 @@
   std::vector<std::string> outputLines() {
     // Deliberately don't flush output stream, the tracer should do that.
     // This is important when clangd crashes.
-    llvm::SmallVector<llvm::StringRef, 4> Lines;
+    llvm::SmallVector<llvm::StringRef> Lines;
     llvm::StringRef(Output).split(Lines, "\r\n");
     return {Lines.begin(), Lines.end()};
   }