Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -71,6 +71,10 @@
   errors/warnings, as the system frameworks might add a method with the same
   selector which could make the message send to ``id`` ambiguous.
 
+- ``-Wtautological-compare`` warning on comparison of unsigned integer and
+  ``0`` constant was adjusted to warn regardless of whether the constant is
+  signed or unsigned.
+
 Non-comprehensive list of changes in this release
 -------------------------------------------------
 
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -8572,26 +8572,49 @@
   if (S.inTemplateInstantiation())
     return;
 
+  // bool values are handled by DiagnoseOutOfRangeComparison().
+
   BinaryOperatorKind op = E->getOpcode();
   if (E->isValueDependent())
     return;
 
-  if (op == BO_LT && IsZero(S, E->getRHS())) {
+  Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
+  Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
+
+  QualType LType = LHS->getType();
+  QualType RType = RHS->getType();
+
+  // if the non-constant size is signed/boolean value/not integer,
+  // then we don't warn here
+  bool BadL = !LType->isIntegerType() || LType->isSignedIntegerType() ||
+              LHS->isKnownToHaveBooleanValue();
+  bool BadR = !RType->isIntegerType() || RType->isSignedIntegerType() ||
+              RHS->isKnownToHaveBooleanValue();
+
+  if (op == BO_LT && IsZero(S, RHS)) {
+    if (BadL)
+      return;
     S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
-      << "< 0" << "false" << HasEnumType(E->getLHS())
-      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
-  } else if (op == BO_GE && IsZero(S, E->getRHS())) {
+      << "< 0" << "false" << HasEnumType(LHS)
+      << LHS->getSourceRange() << RHS->getSourceRange();
+  } else if (op == BO_GE && IsZero(S, RHS)) {
+    if (BadL)
+      return;
     S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
-      << ">= 0" << "true" << HasEnumType(E->getLHS())
-      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
-  } else if (op == BO_GT && IsZero(S, E->getLHS())) {
+      << ">= 0" << "true" << HasEnumType(LHS)
+      << LHS->getSourceRange() << RHS->getSourceRange();
+  } else if (op == BO_GT && IsZero(S, LHS)) {
+    if (BadR)
+      return;
     S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
-      << "0 >" << "false" << HasEnumType(E->getRHS())
-      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
-  } else if (op == BO_LE && IsZero(S, E->getLHS())) {
+      << "0 >" << "false" << HasEnumType(RHS)
+      << LHS->getSourceRange() << RHS->getSourceRange();
+  } else if (op == BO_LE && IsZero(S, LHS)) {
+    if (BadR)
+      return;
     S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
-      << "0 <=" << "true" << HasEnumType(E->getRHS())
-      << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
+      << "0 <=" << "true" << HasEnumType(RHS)
+      << LHS->getSourceRange() << RHS->getSourceRange();
   }
 }
 
@@ -8849,14 +8872,10 @@
         (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
   } else if (!T->hasUnsignedIntegerRepresentation())
       IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
-  
-  // We don't do anything special if this isn't an unsigned integral
-  // comparison:  we're only interested in integral comparisons, and
-  // signed comparisons only happen in cases we don't care to warn about.
-  //
-  // We also don't care about value-dependent expressions or expressions
+
+  // We don't care about value-dependent expressions or expressions
   // whose result is a constant.
-  if (!T->hasUnsignedIntegerRepresentation() || IsComparisonConstant)
+  if (IsComparisonConstant)
     return AnalyzeImpConvsInComparison(S, E);
   
   // Check to see if one of the (unmodified) operands is of different
@@ -8889,6 +8908,12 @@
   if (signedRange.NonNegative)
     return CheckTrivialUnsignedComparison(S, E);
 
+  // We don't do anything special if this isn't an unsigned integral
+  // comparison:  we're only interested in integral comparisons, and
+  // signed comparisons only happen in cases we don't care to warn about.
+  if (!T->hasUnsignedIntegerRepresentation())
+    return AnalyzeImpConvsInComparison(S, E);
+
   // For (in)equality comparisons, if the unsigned operand is a
   // constant which cannot collide with a overflowed signed operand,
   // then reinterpreting the signed operand as unsigned will not
Index: test/Sema/outof-range-constant-compare.c
===================================================================
--- test/Sema/outof-range-constant-compare.c
+++ test/Sema/outof-range-constant-compare.c
@@ -6,6 +6,59 @@
 int main()
 {
     int a = value();
+
+    if (a == 0x0000000000000000L)
+        return 0;
+    if (a != 0x0000000000000000L)
+        return 0;
+    if (a < 0x0000000000000000L)
+        return 0;
+    if (a <= 0x0000000000000000L)
+        return 0;
+    if (a > 0x0000000000000000L)
+        return 0;
+    if (a >= 0x0000000000000000L)
+        return 0;
+
+    if (0x0000000000000000L == a)
+        return 0;
+    if (0x0000000000000000L != a)
+        return 0;
+    if (0x0000000000000000L < a)
+        return 0;
+    if (0x0000000000000000L <= a)
+        return 0;
+    if (0x0000000000000000L > a)
+        return 0;
+    if (0x0000000000000000L >= a)
+        return 0;
+
+    if (a == 0x0000000000000000UL)
+        return 0;
+    if (a != 0x0000000000000000UL)
+        return 0;
+    if (a < 0x0000000000000000UL)
+        return 0;
+    if (a <= 0x0000000000000000UL)
+        return 0;
+    if (a > 0x0000000000000000UL)
+        return 0;
+    if (a >= 0x0000000000000000UL)
+        return 0;
+
+    if (0x0000000000000000UL == a)
+        return 0;
+    if (0x0000000000000000UL != a)
+        return 0;
+    if (0x0000000000000000UL < a)
+        return 0;
+    if (0x0000000000000000UL <= a)
+        return 0;
+    if (0x0000000000000000UL > a)
+        return 0;
+    if (0x0000000000000000UL >= a)
+        return 0;
+
     if (a == 0x1234567812345678L) // expected-warning {{comparison of constant 1311768465173141112 with expression of type 'int' is always false}}
         return 0;
     if (a != 0x1234567812345678L) // expected-warning {{comparison of constant 1311768465173141112 with expression of type 'int' is always true}}
@@ -74,6 +127,7 @@
         return 0;
     if (0x1234567812345678L >= s) // expected-warning {{comparison of constant 1311768465173141112 with expression of type 'short' is always true}}
         return 0;
+
     long l = value();
     if (l == 0x1234567812345678L)
         return 0;
@@ -106,13 +160,13 @@
         return 0;
     if (un != 0x0000000000000000L)
         return 0;
-    if (un < 0x0000000000000000L)
+    if (un < 0x0000000000000000L) // expected-warning {{comparison of unsigned expression < 0 is always false}}
         return 0;
     if (un <= 0x0000000000000000L)
         return 0;
     if (un > 0x0000000000000000L)
         return 0;
-    if (un >= 0x0000000000000000L)
+    if (un >= 0x0000000000000000L) // expected-warning {{comparison of unsigned expression >= 0 is always true}}
         return 0;
 
     if (0x0000000000000000L == un)
@@ -121,19 +175,92 @@
         return 0;
     if (0x0000000000000000L < un)
         return 0;
-    if (0x0000000000000000L <= un)
+    if (0x0000000000000000L <= un) // expected-warning {{comparison of 0 <= unsigned expression is always true}}
         return 0;
-    if (0x0000000000000000L > un)
+    if (0x0000000000000000L > un) // expected-warning {{comparison of 0 > unsigned expression is always false}}
         return 0;
     if (0x0000000000000000L >= un)
         return 0;
-    float fl = 0;
-    if (fl == 0x0000000000000000L) // no warning
-      return 0;
 
-    float dl = 0;
-    if (dl == 0x0000000000000000L) // no warning
-      return 0;
+    if (un == 0x0000000000000000UL)
+        return 0;
+    if (un != 0x0000000000000000UL)
+        return 0;
+    if (un < 0x0000000000000000UL) // expected-warning {{comparison of unsigned expression < 0 is always false}}
+        return 0;
+    if (un <= 0x0000000000000000UL)
+        return 0;
+    if (un > 0x0000000000000000UL)
+        return 0;
+    if (un >= 0x0000000000000000UL) // expected-warning {{comparison of unsigned expression >= 0 is always true}}
+        return 0;
+
+    if (0x0000000000000000UL == un)
+        return 0;
+    if (0x0000000000000000UL != un)
+        return 0;
+    if (0x0000000000000000UL < un)
+        return 0;
+    if (0x0000000000000000UL <= un) // expected-warning {{comparison of 0 <= unsigned expression is always true}}
+        return 0;
+    if (0x0000000000000000UL > un) // expected-warning {{comparison of 0 > unsigned expression is always false}}
+        return 0;
+    if (0x0000000000000000UL >= un)
+        return 0;
+
+    float fl = 0;
+    if (fl == 0x0000000000000000L)
+        return 0;
+    if (fl != 0x0000000000000000L)
+        return 0;
+    if (fl < 0x0000000000000000L)
+        return 0;
+    if (fl <= 0x0000000000000000L)
+        return 0;
+    if (fl > 0x0000000000000000L)
+        return 0;
+    if (fl >= 0x0000000000000000L)
+        return 0;
+
+    if (0x0000000000000000L == fl)
+        return 0;
+    if (0x0000000000000000L != fl)
+        return 0;
+    if (0x0000000000000000L < fl)
+        return 0;
+    if (0x0000000000000000L <= fl)
+        return 0;
+    if (0x0000000000000000L > fl)
+        return 0;
+    if (0x0000000000000000L >= fl)
+        return 0;
+
+    double dl = 0;
+    if (dl == 0x0000000000000000L)
+        return 0;
+    if (dl != 0x0000000000000000L)
+        return 0;
+    if (dl < 0x0000000000000000L)
+        return 0;
+    if (dl <= 0x0000000000000000L)
+        return 0;
+    if (dl > 0x0000000000000000L)
+        return 0;
+    if (dl >= 0x0000000000000000L)
+        return 0;
+
+    if (0x0000000000000000L == dl)
+        return 0;
+    if (0x0000000000000000L != dl)
+        return 0;
+    if (0x0000000000000000L < dl)
+        return 0;
+    if (0x0000000000000000L <= dl)
+        return 0;
+    if (0x0000000000000000L > dl)
+        return 0;
+    if (0x0000000000000000L >= dl)
+        return 0;
 
     enum E {
     yes,