Index: clang/include/clang/Basic/SourceManager.h
===================================================================
--- clang/include/clang/Basic/SourceManager.h
+++ clang/include/clang/Basic/SourceManager.h
@@ -1390,10 +1390,14 @@
   /// returns zero if the column number isn't known.  This may only be called
   /// on a file sloc, so you must choose a spelling or expansion location
   /// before calling this method.
+  /// /param UseTabsStopOption when true tabs will count for TabsStop
+  /// (-ftabstop=x). otherwise tabs are counted as 1.
   unsigned getColumnNumber(FileID FID, unsigned FilePos,
-                           bool *Invalid = nullptr) const;
+                           bool *Invalid = nullptr,
+                           bool UseTabsStopOption = false) const;
   unsigned getSpellingColumnNumber(SourceLocation Loc,
-                                   bool *Invalid = nullptr) const;
+                                   bool *Invalid = nullptr,
+                                   bool UseTabsStopOption = false) const;
   unsigned getExpansionColumnNumber(SourceLocation Loc,
                                     bool *Invalid = nullptr) const;
   unsigned getPresumedColumnNumber(SourceLocation Loc,
Index: clang/lib/Basic/SourceManager.cpp
===================================================================
--- clang/lib/Basic/SourceManager.cpp
+++ clang/lib/Basic/SourceManager.cpp
@@ -1149,7 +1149,8 @@
 /// getColumnNumber - Return the column # for the specified file position.
 /// this is significantly cheaper to compute than the line number.
 unsigned SourceManager::getColumnNumber(FileID FID, unsigned FilePos,
-                                        bool *Invalid) const {
+                                        bool *Invalid,
+                                        bool UseTabsStopOption) const {
   bool MyInvalid = false;
   const llvm::MemoryBuffer *MemBuf = getBuffer(FID, &MyInvalid);
   if (Invalid)
@@ -1170,7 +1171,8 @@
   // that to lookup the start of the line instead of searching for it.
   if (LastLineNoFileIDQuery == FID &&
       LastLineNoContentCache->SourceLineCache != nullptr &&
-      LastLineNoResult < LastLineNoContentCache->NumLines) {
+      LastLineNoResult < LastLineNoContentCache->NumLines &&
+      !UseTabsStopOption) {
     unsigned *SourceLineCache = LastLineNoContentCache->SourceLineCache;
     unsigned LineStart = SourceLineCache[LastLineNoResult - 1];
     unsigned LineEnd = SourceLineCache[LastLineNoResult];
@@ -1187,10 +1189,22 @@
     }
   }
 
+  unsigned TabStop =
+      UseTabsStopOption ? getDiagnostics().getDiagnosticOptions().TabStop : 1;
+
   unsigned LineStart = FilePos;
-  while (LineStart && Buf[LineStart-1] != '\n' && Buf[LineStart-1] != '\r')
+  while (LineStart && Buf[LineStart - 1] != '\n' && Buf[LineStart - 1] != '\r')
     --LineStart;
-  return FilePos-LineStart+1;
+  if (TabStop == 1)
+    return FilePos - LineStart + 1;
+  unsigned VirtualCharCount = 0;
+  while (LineStart <= FilePos) {
+    LineStart++;
+    VirtualCharCount = Buf[LineStart - 1] == '\t'
+                           ? llvm::alignTo(VirtualCharCount + 1, TabStop)
+                           : VirtualCharCount + 1;
+  }
+  return VirtualCharCount;
 }
 
 // isInvalid - Return the result of calling loc.isInvalid(), and
@@ -1204,10 +1218,13 @@
 }
 
 unsigned SourceManager::getSpellingColumnNumber(SourceLocation Loc,
-                                                bool *Invalid) const {
-  if (isInvalid(Loc, Invalid)) return 0;
+                                                bool *Invalid,
+                                                bool UseTabsStopOption) const {
+  if (isInvalid(Loc, Invalid))
+    return 0;
   std::pair<FileID, unsigned> LocInfo = getDecomposedSpellingLoc(Loc);
-  return getColumnNumber(LocInfo.first, LocInfo.second, Invalid);
+  return getColumnNumber(LocInfo.first, LocInfo.second, Invalid,
+                         UseTabsStopOption);
 }
 
 unsigned SourceManager::getExpansionColumnNumber(SourceLocation Loc,
Index: clang/lib/Parse/ParseStmt.cpp
===================================================================
--- clang/lib/Parse/ParseStmt.cpp
+++ clang/lib/Parse/ParseStmt.cpp
@@ -1226,11 +1226,16 @@
       P.MisleadingIndentationElseLoc = SourceLocation();
       return;
     }
+    if (Kind == MSK_else)
+      P.MisleadingIndentationElseLoc = SourceLocation();
 
     SourceManager &SM = P.getPreprocessor().getSourceManager();
-    unsigned PrevColNum = SM.getSpellingColumnNumber(PrevLoc);
-    unsigned CurColNum = SM.getSpellingColumnNumber(Tok.getLocation());
-    unsigned StmtColNum = SM.getSpellingColumnNumber(StmtLoc);
+    unsigned PrevColNum =
+        SM.getSpellingColumnNumber(PrevLoc, nullptr, /*UseTabStop*/ true);
+    unsigned CurColNum = SM.getSpellingColumnNumber(Tok.getLocation(), nullptr,
+                                                    /*UseTabStop*/ true);
+    unsigned StmtColNum =
+        SM.getSpellingColumnNumber(StmtLoc, nullptr, /*UseTabStop*/ true);
 
     if (PrevColNum != 0 && CurColNum != 0 && StmtColNum != 0 &&
         ((PrevColNum > StmtColNum && PrevColNum == CurColNum) ||
Index: clang/test/Parser/warn-misleading-indentation.cpp
===================================================================
--- clang/test/Parser/warn-misleading-indentation.cpp
+++ clang/test/Parser/warn-misleading-indentation.cpp
@@ -1,7 +1,9 @@
-// RUN: %clang_cc1 -x c -fsyntax-only -verify %s
-// RUN: %clang_cc1 -x c -fsyntax-only -verify -Wmisleading-indentation -DWITH_WARN %s
-// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify -Wall -Wno-unused -DWITH_WARN -DCXX17 %s
-// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify -Wall -Wno-unused -Wno-misleading-indentation -DCXX17 %s
+// RUNA: %clang_cc1 -x c -fsyntax-only -verify %s
+// RUNA: %clang_cc1 -x c -fsyntax-only -verify -Wmisleading-indentation -DWITH_WARN -ftabstop 8 -DTAB_SIZE=8 %s
+// RUNA: %clang_cc1 -std=c++17 -fsyntax-only -verify -Wall -Wno-unused -DWITH_WARN -DCXX17 %s
+// RUNA: %clang_cc1 -std=c++17 -fsyntax-only -verify -Wall -Wno-unused -Wno-misleading-indentation -DCXX17 -ftabstop 4 -DTAB_SIZE=4 %s
+// RUNA: %clang_cc1 -x c -fsyntax-only -verify -Wall -Wno-unused -DWITH_WARN -ftabstop 1 -DTAB_SIZE=1 %s
+// RUN: %clang_cc1 -std=c++17 -fsyntax-only -verify -Wall -Wno-unused -Wmisleading-indentation -DCXX17 -DWITH_WARN -ftabstop 2 -DTAB_SIZE=2 %s
 
 #ifndef WITH_WARN
 // expected-no-diagnostics
@@ -205,4 +207,37 @@
     i = 4;
     }
     return;
-}
\ No newline at end of file
+}
+
+int a4()
+{
+	if (0)
+		return 1;
+ 	return 0;
+#if (TAB_SIZE == 1)
+// expected-warning@-2 {{misleading indentation; statement is not part of the previous 'if'}}
+// expected-note@-5 {{here}}
+#endif 
+}
+
+int a5()
+{
+	if (0)
+		return 1;
+		return 0;
+#if WITH_WARN
+// expected-warning@-2 {{misleading indentation; statement is not part of the previous 'if'}}
+// expected-note@-5 {{here}}
+#endif
+}
+
+int a6()
+{
+	if (0)
+		return 1;
+    	return 0;
+#if (TAB_SIZE == 4)
+// expected-warning@-2 {{misleading indentation; statement is not part of the previous 'if'}}
+// expected-note@-5 {{here}}
+#endif
+}