diff --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
index 3f3f1bb65c2c19..73e6353109d921 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/include/clang/Basic/SourceManager.h
@@ -900,22 +900,26 @@ class SourceManager : public RefCountedBase<SourceManager> {
   FileID getOrCreateFileID(const FileEntry *SourceFile,
                            SrcMgr::CharacteristicKind FileCharacter);
 
-  /// Return a new SourceLocation that encodes the
-  /// fact that a token from SpellingLoc should actually be referenced from
-  /// ExpansionLoc, and that it represents the expansion of a macro argument
-  /// into the function-like macro body.
-  SourceLocation createMacroArgExpansionLoc(SourceLocation Loc,
+  /// Creates an expansion SLocEntry for the substitution of an argument into a
+  /// function-like macro's body. Returns the start of the expansion.
+  ///
+  /// The macro argument was written at \p SpellingLoc with length \p Length.
+  /// \p ExpansionLoc is the parameter name in the (expanded) macro body.
+  SourceLocation createMacroArgExpansionLoc(SourceLocation SpellingLoc,
                                             SourceLocation ExpansionLoc,
-                                            unsigned TokLength);
+                                            unsigned Length);
 
-  /// Return a new SourceLocation that encodes the fact
-  /// that a token from SpellingLoc should actually be referenced from
-  /// ExpansionLoc.
-  SourceLocation
-  createExpansionLoc(SourceLocation Loc, SourceLocation ExpansionLocStart,
-                     SourceLocation ExpansionLocEnd, unsigned TokLength,
-                     bool ExpansionIsTokenRange = true, int LoadedID = 0,
-                     SourceLocation::UIntTy LoadedOffset = 0);
+  /// Creates an expansion SLocEntry for a macro use. Returns its start.
+  ///
+  /// The macro body begins at \p SpellingLoc with length \p Length.
+  /// The macro use spans [ExpansionLocStart, ExpansionLocEnd].
+  SourceLocation createExpansionLoc(SourceLocation SpellingLoc,
+                                    SourceLocation ExpansionLocStart,
+                                    SourceLocation ExpansionLocEnd,
+                                    unsigned Length,
+                                    bool ExpansionIsTokenRange = true,
+                                    int LoadedID = 0,
+                                    SourceLocation::UIntTy LoadedOffset = 0);
 
   /// Return a new SourceLocation that encodes that the token starting
   /// at \p TokenStart ends prematurely at \p TokenEnd.
@@ -1803,7 +1807,7 @@ class SourceManager : public RefCountedBase<SourceManager> {
   /// the SLocEntry table and producing a source location that refers to it.
   SourceLocation
   createExpansionLocImpl(const SrcMgr::ExpansionInfo &Expansion,
-                         unsigned TokLength, int LoadedID = 0,
+                         unsigned Length, int LoadedID = 0,
                          SourceLocation::UIntTy LoadedOffset = 0);
 
   /// Return true if the specified FileID contains the
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 537ccc22ed050a..e2294088908c53 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -9293,13 +9293,13 @@ Expected<FileID> ASTImporter::Import(FileID FromID, bool IsBuiltin) {
     ExpectedSLoc ToExLocS = Import(FromEx.getExpansionLocStart());
     if (!ToExLocS)
       return ToExLocS.takeError();
-    unsigned TokenLen = FromSM.getFileIDSize(FromID);
+    unsigned ExLength = FromSM.getFileIDSize(FromID);
     SourceLocation MLoc;
     if (FromEx.isMacroArgExpansion()) {
-      MLoc = ToSM.createMacroArgExpansionLoc(*ToSpLoc, *ToExLocS, TokenLen);
+      MLoc = ToSM.createMacroArgExpansionLoc(*ToSpLoc, *ToExLocS, ExLength);
     } else {
       if (ExpectedSLoc ToExLocE = Import(FromEx.getExpansionLocEnd()))
-        MLoc = ToSM.createExpansionLoc(*ToSpLoc, *ToExLocS, *ToExLocE, TokenLen,
+        MLoc = ToSM.createExpansionLoc(*ToSpLoc, *ToExLocS, *ToExLocE, ExLength,
                                        FromEx.isExpansionTokenRange());
       else
         return ToExLocE.takeError();
diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index ec3e35595bb75c..98e731eb12e62f 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -629,23 +629,21 @@ FileID SourceManager::createFileIDImpl(ContentCache &File, StringRef Filename,
   return LastFileIDLookup = FID;
 }
 
-SourceLocation
-SourceManager::createMacroArgExpansionLoc(SourceLocation SpellingLoc,
-                                          SourceLocation ExpansionLoc,
-                                          unsigned TokLength) {
+SourceLocation SourceManager::createMacroArgExpansionLoc(
+    SourceLocation SpellingLoc, SourceLocation ExpansionLoc, unsigned Length) {
   ExpansionInfo Info = ExpansionInfo::createForMacroArg(SpellingLoc,
                                                         ExpansionLoc);
-  return createExpansionLocImpl(Info, TokLength);
+  return createExpansionLocImpl(Info, Length);
 }
 
 SourceLocation SourceManager::createExpansionLoc(
     SourceLocation SpellingLoc, SourceLocation ExpansionLocStart,
-    SourceLocation ExpansionLocEnd, unsigned TokLength,
+    SourceLocation ExpansionLocEnd, unsigned Length,
     bool ExpansionIsTokenRange, int LoadedID,
     SourceLocation::UIntTy LoadedOffset) {
   ExpansionInfo Info = ExpansionInfo::create(
       SpellingLoc, ExpansionLocStart, ExpansionLocEnd, ExpansionIsTokenRange);
-  return createExpansionLocImpl(Info, TokLength, LoadedID, LoadedOffset);
+  return createExpansionLocImpl(Info, Length, LoadedID, LoadedOffset);
 }
 
 SourceLocation SourceManager::createTokenSplitLoc(SourceLocation Spelling,
@@ -660,7 +658,7 @@ SourceLocation SourceManager::createTokenSplitLoc(SourceLocation Spelling,
 
 SourceLocation
 SourceManager::createExpansionLocImpl(const ExpansionInfo &Info,
-                                      unsigned TokLength, int LoadedID,
+                                      unsigned Length, int LoadedID,
                                       SourceLocation::UIntTy LoadedOffset) {
   if (LoadedID < 0) {
     assert(LoadedID != -1 && "Loading sentinel FileID");
@@ -672,12 +670,12 @@ SourceManager::createExpansionLocImpl(const ExpansionInfo &Info,
     return SourceLocation::getMacroLoc(LoadedOffset);
   }
   LocalSLocEntryTable.push_back(SLocEntry::get(NextLocalOffset, Info));
-  assert(NextLocalOffset + TokLength + 1 > NextLocalOffset &&
-         NextLocalOffset + TokLength + 1 <= CurrentLoadedOffset &&
+  assert(NextLocalOffset + Length + 1 > NextLocalOffset &&
+         NextLocalOffset + Length + 1 <= CurrentLoadedOffset &&
          "Ran out of source locations!");
   // See createFileID for that +1.
-  NextLocalOffset += TokLength + 1;
-  return SourceLocation::getMacroLoc(NextLocalOffset - (TokLength + 1));
+  NextLocalOffset += Length + 1;
+  return SourceLocation::getMacroLoc(NextLocalOffset - (Length + 1));
 }
 
 llvm::Optional<llvm::MemoryBufferRef>