Index: lib/MC/MCParser/AsmParser.cpp
===================================================================
--- lib/MC/MCParser/AsmParser.cpp
+++ lib/MC/MCParser/AsmParser.cpp
@@ -689,13 +689,14 @@
       // Variable symbols may not be marked as defined, so check those
       // explicitly. If we know it's a variable, we have a definition for
       // the purposes of this check.
-      if (Sym->isTemporary() && !Sym->isVariable() && !Sym->isDefined())
+      if (Sym->isTemporary() && !Sym->isVariable() &&
+          !Sym->isDefined(/*SetUsed*/ false))
         // FIXME: We would really like to refer back to where the symbol was
         // first referenced for a source location. We need to add something
         // to track that. Currently, we just point to the end of the file.
-        printMessage(
-            getLexer().getLoc(), SourceMgr::DK_Error,
-            "assembler local symbol '" + Sym->getName() + "' not defined");
+        printMessage(getLexer().getLoc(), SourceMgr::DK_Error,
+                     "assembler local symbol '" + Sym->getName() +
+                         "' not defined");
     }
   }
 
@@ -867,11 +868,12 @@
 
     // If this is an absolute variable reference, substitute it now to preserve
     // semantics in the face of reassignment.
-    if (Sym->isVariable() && isa<MCConstantExpr>(Sym->getVariableValue())) {
+    if (Sym->isVariable() &&
+        isa<MCConstantExpr>(Sym->getVariableValue(/*SetUsed*/ false))) {
       if (Variant)
         return Error(EndLoc, "unexpected modifier on variable reference");
 
-      Res = Sym->getVariableValue();
+      Res = Sym->getVariableValue(/*SetUsed*/ false);
       return false;
     }
 
@@ -903,7 +905,7 @@
         MCSymbol *Sym =
             Ctx.getDirectionalLocalSymbol(IntVal, IDVal == "b");
         Res = MCSymbolRefExpr::create(Sym, Variant, getContext());
-        if (IDVal == "b" && Sym->isUndefined())
+        if (IDVal == "b" && Sym->isUndefined(/*SetUsed*/ false))
           return Error(Loc, "invalid reference to undefined symbol");
         EndLoc = Lexer.getTok().getEndLoc();
         Lex(); // Eat identifier.
@@ -1346,7 +1348,7 @@
 
     Sym->redefineIfPossible();
 
-    if (!Sym->isUndefined() || Sym->isVariable())
+    if (!Sym->isUndefined(/*SetUsed*/ false) || Sym->isVariable())
       return Error(IDLoc, "invalid symbol redefinition");
 
     // Emit the label.
@@ -3752,7 +3754,7 @@
     return Error(Pow2AlignmentLoc, "invalid '.comm' or '.lcomm' directive "
                                    "alignment, can't be less than zero");
 
-  if (!Sym->isUndefined())
+  if (!Sym->isUndefined(/*SetUsed*/ false))
     return Error(IDLoc, "invalid symbol redefinition");
 
   // Create the Symbol as a common or local common with Size and Pow2Alignment
@@ -4002,9 +4004,9 @@
     MCSymbol *Sym = getContext().lookupSymbol(Name);
 
     if (expect_defined)
-      TheCondState.CondMet = (Sym && !Sym->isUndefined());
+      TheCondState.CondMet = (Sym && !Sym->isUndefined(/*SetUsed*/ false));
     else
-      TheCondState.CondMet = (!Sym || Sym->isUndefined());
+      TheCondState.CondMet = (!Sym || Sym->isUndefined(/*SetUsed*/ false));
     TheCondState.Ignore = !TheCondState.CondMet;
   }
 
@@ -4760,7 +4762,8 @@
     const MCSymbol &S =
         static_cast<const MCSymbolRefExpr *>(Value)->getSymbol();
     if (S.isVariable())
-      return isSymbolUsedInExpression(Sym, S.getVariableValue());
+      return isSymbolUsedInExpression(Sym,
+                                      S.getVariableValue(/*SetUsed*/ false));
     return &S == Sym;
   }
   case MCExpr::Unary:
@@ -4805,21 +4808,20 @@
     // FIXME: Diagnose assignment to protected identifier (e.g., register name).
     if (isSymbolUsedInExpression(Sym, Value))
       return Parser.Error(EqualLoc, "Recursive use of '" + Name + "'");
-    else if (Sym->isUndefined() && !Sym->isUsed() && !Sym->isVariable())
+    else if (Sym->isUndefined(/*SetUsed*/ false) && !Sym->isUsed() &&
+             !Sym->isVariable())
       ; // Allow redefinitions of undefined symbols only used in directives.
     else if (Sym->isVariable() && !Sym->isUsed() && allow_redef)
       ; // Allow redefinitions of variables that haven't yet been used.
-    else if (!Sym->isUndefined() && (!Sym->isVariable() || !allow_redef))
+    else if (!Sym->isUndefined(/*SetUsed*/ false) &&
+             (!Sym->isVariable() || !allow_redef))
       return Parser.Error(EqualLoc, "redefinition of '" + Name + "'");
     else if (!Sym->isVariable())
       return Parser.Error(EqualLoc, "invalid assignment to '" + Name + "'");
-    else if (!isa<MCConstantExpr>(Sym->getVariableValue()))
+    else if (!isa<MCConstantExpr>(Sym->getVariableValue(/*SetUsed*/ false)))
       return Parser.Error(EqualLoc,
                           "invalid reassignment of non-absolute variable '" +
                               Name + "'");
-
-    // Don't count these checks as uses.
-    Sym->setUsed(false);
   } else if (Name == ".") {
     if (Parser.getStreamer().EmitValueToOffset(Value, 0)) {
       Parser.Error(EqualLoc, "expected absolute expression");
Index: test/MC/AsmParser/reassign.s
===================================================================
--- /dev/null
+++ test/MC/AsmParser/reassign.s
@@ -0,0 +1,12 @@
+// RUN: llvm-mc -triple i386-unknown-unknown %s | FileCheck %s
+
+	.text
+bar:
+
+	.data
+.globl foo
+.set   foo, bar
+.globl foo
+.set   foo, bar
+
+// CHECK-NOT: invalid reassignment of non-absolute variable