diff --git a/clang/lib/AST/SelectorLocationsKind.cpp b/clang/lib/AST/SelectorLocationsKind.cpp
--- a/clang/lib/AST/SelectorLocationsKind.cpp
+++ b/clang/lib/AST/SelectorLocationsKind.cpp
@@ -27,7 +27,7 @@
     if (EndLoc.isInvalid())
       return SourceLocation();
     IdentifierInfo *II = Sel.getIdentifierInfoForSlot(0);
-    unsigned Len = II ? II->getLength() : 0;
+    SourceLocation::UIntTy Len = II ? II->getLength() : 0;
     return EndLoc.getLocWithOffset(-Len);
   }
 
@@ -35,7 +35,8 @@
   if (ArgLoc.isInvalid())
     return SourceLocation();
   IdentifierInfo *II = Sel.getIdentifierInfoForSlot(Index);
-  unsigned Len = /* selector id */ (II ? II->getLength() : 0) + /* ':' */ 1;
+  SourceLocation::UIntTy Len =
+      /* selector id */ (II ? II->getLength() : 0) + /* ':' */ 1;
   if (WithArgSpace)
     ++Len;
   return ArgLoc.getLocWithOffset(-Len);
diff --git a/clang/lib/CodeGen/CoverageMappingGen.cpp b/clang/lib/CodeGen/CoverageMappingGen.cpp
--- a/clang/lib/CodeGen/CoverageMappingGen.cpp
+++ b/clang/lib/CodeGen/CoverageMappingGen.cpp
@@ -232,8 +232,10 @@
 
   /// Return the start location of an included file or expanded macro.
   SourceLocation getStartOfFileOrMacro(SourceLocation Loc) {
-    if (Loc.isMacroID())
-      return Loc.getLocWithOffset(-SM.getFileOffset(Loc));
+    if (Loc.isMacroID()) {
+      SourceLocation::UIntTy FileOffset = SM.getFileOffset(Loc);
+      return Loc.getLocWithOffset(-FileOffset);
+    }
     return SM.getLocForStartOfFile(SM.getFileID(Loc));
   }
 
diff --git a/clang/lib/Format/FormatTokenLexer.cpp b/clang/lib/Format/FormatTokenLexer.cpp
--- a/clang/lib/Format/FormatTokenLexer.cpp
+++ b/clang/lib/Format/FormatTokenLexer.cpp
@@ -832,7 +832,8 @@
   FormatTok = new (Allocator.Allocate()) FormatToken;
   readRawToken(*FormatTok);
   SourceLocation WhitespaceStart =
-      FormatTok->Tok.getLocation().getLocWithOffset(-TrailingWhitespace);
+      FormatTok->Tok.getLocation().getLocWithOffset(
+          -static_cast<SourceLocation::UIntTy>(TrailingWhitespace));
   FormatTok->IsFirst = IsFirstToken;
   IsFirstToken = false;
 
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -510,24 +510,29 @@
                                               const SourceManager &SM,
                                               const LangOptions &LangOpts) {
   assert(Loc.isFileID());
-  std::pair<FileID, unsigned> LocInfo = SM.getDecomposedLoc(Loc);
-  if (LocInfo.first.isInvalid())
+  FileID LocFileID;
+  SourceLocation::UIntTy LocOffset;
+  std::tie(LocFileID, LocOffset) = SM.getDecomposedLoc(Loc);
+  if (LocFileID.isInvalid())
     return Loc;
 
   bool Invalid = false;
-  StringRef Buffer = SM.getBufferData(LocInfo.first, &Invalid);
+  StringRef Buffer = SM.getBufferData(LocFileID, &Invalid);
   if (Invalid)
     return Loc;
 
+  if (LocOffset > Buffer.size())
+    return Loc;
+
   // Back up from the current location until we hit the beginning of a line
   // (or the buffer). We'll relex from that point.
-  const char *StrData = Buffer.data() + LocInfo.second;
-  const char *LexStart = findBeginningOfLine(Buffer, LocInfo.second);
+  const char *StrData = Buffer.data() + LocOffset;
+  const char *LexStart = findBeginningOfLine(Buffer, LocOffset);
   if (!LexStart || LexStart == StrData)
     return Loc;
 
   // Create a lexer starting at the beginning of this token.
-  SourceLocation LexerStartLoc = Loc.getLocWithOffset(-LocInfo.second);
+  SourceLocation LexerStartLoc = Loc.getLocWithOffset(-LocOffset);
   Lexer TheLexer(LexerStartLoc, LangOpts, Buffer.data(), LexStart,
                  Buffer.end());
   TheLexer.SetCommentRetentionState(true);
@@ -565,12 +570,12 @@
 
   SourceLocation FileLoc = SM.getSpellingLoc(Loc);
   SourceLocation BeginFileLoc = getBeginningOfFileToken(FileLoc, SM, LangOpts);
-  std::pair<FileID, unsigned> FileLocInfo = SM.getDecomposedLoc(FileLoc);
-  std::pair<FileID, unsigned> BeginFileLocInfo =
-      SM.getDecomposedLoc(BeginFileLoc);
-  assert(FileLocInfo.first == BeginFileLocInfo.first &&
-         FileLocInfo.second >= BeginFileLocInfo.second);
-  return Loc.getLocWithOffset(BeginFileLocInfo.second - FileLocInfo.second);
+  FileID FID, BeginFID;
+  SourceLocation::UIntTy FileOffset, BeginFileOffset;
+  std::tie(FID, FileOffset) = SM.getDecomposedLoc(FileLoc);
+  std::tie(BeginFID, BeginFileOffset) = SM.getDecomposedLoc(BeginFileLoc);
+  assert(FID == BeginFID && FileOffset >= BeginFileOffset);
+  return Loc.getLocWithOffset(BeginFileOffset - FileOffset);
 }
 
 namespace {
diff --git a/clang/lib/Parse/ParseStmtAsm.cpp b/clang/lib/Parse/ParseStmtAsm.cpp
--- a/clang/lib/Parse/ParseStmtAsm.cpp
+++ b/clang/lib/Parse/ParseStmtAsm.cpp
@@ -185,7 +185,8 @@
   if (TokIndex < AsmToks.size()) {
     const Token &Tok = AsmToks[TokIndex];
     Loc = Tok.getLocation();
-    Loc = Loc.getLocWithOffset(Offset - TokOffset);
+    Loc = Loc.getLocWithOffset(static_cast<SourceLocation::UIntTy>(Offset) -
+                               TokOffset);
   }
   return Loc;
 }
diff --git a/clang/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp b/clang/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
--- a/clang/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
+++ b/clang/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
@@ -1081,8 +1081,8 @@
   // Highlight the range.  Make the span tag the outermost tag for the
   // selected range.
 
-  SourceLocation E =
-    InstantiationEnd.getLocWithOffset(EndColNo - OldEndColNo);
+  SourceLocation E = InstantiationEnd.getLocWithOffset(
+      static_cast<SourceLocation::UIntTy>(EndColNo) - OldEndColNo);
 
   html::HighlightRange(R, InstantiationStart, E, HighlightStart, HighlightEnd);
 }