diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index df327e7e5097..d1e127b22bd6 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2340,6 +2340,14 @@ def warn_division_by_zero : Warning<"division by zero is undefined">;
 def warn_remainder_by_zero : Warning<"remainder by zero is undefined">;
 def warn_shift_negative : Warning<"shift count is negative">;
 def warn_shift_gt_typewidth : Warning<"shift count >= width of type">;
+def warn_shift_result_gt_typewidth : Warning<
+  "shift result (%0) requires %1 bits to represent, but the promoted type of "
+  "the shift expression is %2 with only %3 bits">,
+   InGroup<DiagGroup<"shift-overflow">>;
+def warn_shift_result_overrides_sign_bit : Warning<
+  "shift result (%0) overrides the sign bit of the promoted type of the shift "
+  "expression (%1) and becomes negative">,
+  InGroup<DiagGroup<"shift-sign-overflow">>, DefaultIgnore;
 
 def warn_precedence_bitwise_rel : Warning<
   "%0 has lower precedence than %1; %1 will be evaluated first">,
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 6b74b863a8c1..1cc20b60f79e 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -4790,7 +4790,8 @@ public:
   QualType CheckSubtractionOperands( // C99 6.5.6
     Expr *&lex, Expr *&rex, SourceLocation OpLoc, QualType* CompLHSTy = 0);
   QualType CheckShiftOperands( // C99 6.5.7
-    Expr *&lex, Expr *&rex, SourceLocation OpLoc, bool isCompAssign = false);
+    Expr *&lex, Expr *&rex, SourceLocation OpLoc, unsigned Opc,
+    bool isCompAssign = false);
   QualType CheckCompareOperands( // C99 6.5.8/9
     Expr *&lex, Expr *&rex, SourceLocation OpLoc, unsigned Opc,
                                 bool isRelational);
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 1ba8ea62b416..076ffeb26878 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6626,9 +6626,61 @@ static bool isScopedEnumerationType(QualType T) {
   return false;
 }
 
+static void DiagnoseBadShiftValues(Sema& S, Expr *&lex, Expr *&rex,
+                                   SourceLocation Loc, unsigned Opc,
+                                   QualType LHSTy) {
+  llvm::APSInt Right;
+  // Check right/shifter operand
+  if (rex->isValueDependent() || !rex->isIntegerConstantExpr(Right, S.Context))
+    return;
+
+  if (Right.isNegative()) {
+    S.Diag(Loc, diag::warn_shift_negative) << rex->getSourceRange();
+    return;
+  }
+  llvm::APInt LeftBits(Right.getBitWidth(),
+                       S.Context.getTypeSize(lex->getType()));
+  if (Right.uge(LeftBits)) {
+    S.Diag(Loc, diag::warn_shift_gt_typewidth) << rex->getSourceRange();
+    return;
+  }
+  if (Opc != BO_Shl)
+    return;
+
+  // When left shifting an ICE which is signed, we can check for overflow which
+  // according to C++ has undefined behavior ([expr.shift] 5.8/2). Unsigned
+  // integers have defined behavior modulo one more than the maximum value
+  // representable in the result type, so never warn for those.
+  llvm::APSInt Left;
+  if (!lex->isIntegerConstantExpr(Left, S.Context) ||
+      LHSTy->hasUnsignedIntegerRepresentation())
+    return;
+  llvm::APInt ResultBits =
+      static_cast<llvm::APInt&>(Right) + Left.getMinSignedBits();
+  if (LeftBits.uge(ResultBits))
+    return;
+  llvm::APSInt Result = Left.extend(ResultBits.getLimitedValue());
+  Result = Result.shl(Right);
+
+  // If we are only missing a sign bit, this is less likely to result in actual
+  // bugs -- if the result is cast back to an unsigned type, it will have the
+  // expected value. Thus we place this behind a different warning that can be
+  // turned off separately if needed.
+  if (LeftBits == ResultBits - 1) {
+    S.Diag(Loc, diag::warn_shift_result_overrides_sign_bit)
+        << Result.toString(10) << LHSTy
+        << lex->getSourceRange() << rex->getSourceRange();
+    return;
+  }
+
+  S.Diag(Loc, diag::warn_shift_result_gt_typewidth)
+    << Result.toString(10) << Result.getMinSignedBits() << LHSTy
+    << Left.getBitWidth() << lex->getSourceRange() << rex->getSourceRange();
+}
+
 // C99 6.5.7
 QualType Sema::CheckShiftOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
-                                  bool isCompAssign) {
+                                  unsigned Opc, bool isCompAssign) {
   // C99 6.5.7p2: Each of the operands shall have integer type.
   if (!lex->getType()->hasIntegerRepresentation() || 
       !rex->getType()->hasIntegerRepresentation())
@@ -6659,19 +6711,7 @@ QualType Sema::CheckShiftOperands(Expr *&lex, Expr *&rex, SourceLocation Loc,
   UsualUnaryConversions(rex);
 
   // Sanity-check shift operands
-  llvm::APSInt Right;
-  // Check right/shifter operand
-  if (!rex->isValueDependent() &&
-      rex->isIntegerConstantExpr(Right, Context)) {
-    if (Right.isNegative())
-      Diag(Loc, diag::warn_shift_negative) << rex->getSourceRange();
-    else {
-      llvm::APInt LeftBits(Right.getBitWidth(),
-                          Context.getTypeSize(lex->getType()));
-      if (Right.uge(LeftBits))
-        Diag(Loc, diag::warn_shift_gt_typewidth) << rex->getSourceRange();
-    }
-  }
+  DiagnoseBadShiftValues(*this, lex, rex, Loc, Opc, LHSTy);
 
   // "The type of the result is that of the promoted left operand."
   return LHSTy;
@@ -7958,7 +7998,7 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
     break;
   case BO_Shl:
   case BO_Shr:
-    ResultTy = CheckShiftOperands(lhs, rhs, OpLoc);
+    ResultTy = CheckShiftOperands(lhs, rhs, OpLoc, Opc);
     break;
   case BO_LE:
   case BO_LT:
@@ -8005,7 +8045,7 @@ ExprResult Sema::CreateBuiltinBinOp(SourceLocation OpLoc,
     break;
   case BO_ShlAssign:
   case BO_ShrAssign:
-    CompResultTy = CheckShiftOperands(lhs, rhs, OpLoc, true);
+    CompResultTy = CheckShiftOperands(lhs, rhs, OpLoc, Opc, true);
     CompLHSTy = CompResultTy;
     if (!CompResultTy.isNull())
       ResultTy = CheckAssignmentOperands(lhs, rhs, OpLoc, CompResultTy);
diff --git a/clang/test/Analysis/retain-release-basic-store.m b/clang/test/Analysis/retain-release-basic-store.m
index 751dca0ce30b..8c05efef66ee 100644
--- a/clang/test/Analysis/retain-release-basic-store.m
+++ b/clang/test/Analysis/retain-release-basic-store.m
@@ -69,7 +69,7 @@ extern DADiskRef DADiskCopyWholeDisk( DADiskRef disk );
 @interface NSAppleEventManager : NSObject {
 }
 @end enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );
diff --git a/clang/test/Analysis/retain-release-gc-only.m b/clang/test/Analysis/retain-release-gc-only.m
index 6f1dd92df997..7d7c58fbcd51 100644
--- a/clang/test/Analysis/retain-release-gc-only.m
+++ b/clang/test/Analysis/retain-release-gc-only.m
@@ -189,7 +189,7 @@ CVTimeStamp;
 }
 typedef int CIFormat;
 @end  enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );
diff --git a/clang/test/Analysis/retain-release-region-store.m b/clang/test/Analysis/retain-release-region-store.m
index 05b91fcf5c56..ec765e3fe809 100644
--- a/clang/test/Analysis/retain-release-region-store.m
+++ b/clang/test/Analysis/retain-release-region-store.m
@@ -75,7 +75,7 @@ extern DADiskRef DADiskCopyWholeDisk( DADiskRef disk );
 @interface NSAppleEventManager : NSObject {
 }
 @end enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );
diff --git a/clang/test/Analysis/retain-release.m b/clang/test/Analysis/retain-release.m
index 81e015f5fc44..71e1620aa534 100644
--- a/clang/test/Analysis/retain-release.m
+++ b/clang/test/Analysis/retain-release.m
@@ -217,7 +217,7 @@ CVTimeStamp;
 }
 typedef int CIFormat;
 @end  enum {
-kDAReturnSuccess = 0,     kDAReturnError = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3e)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
+kDAReturnSuccess = 0,     kDAReturnError = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x01,     kDAReturnBusy = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x02,     kDAReturnBadArgument = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x03,     kDAReturnExclusiveAccess = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x04,     kDAReturnNoResources = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x05,     kDAReturnNotFound = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x06,     kDAReturnNotMounted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x07,     kDAReturnNotPermitted = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x08,     kDAReturnNotPrivileged = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x09,     kDAReturnNotReady = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0A,     kDAReturnNotWritable = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0B,     kDAReturnUnsupported = (((0x3eU)&0x3f)<<26) | (((0x368)&0xfff)<<14) | 0x0C };
 typedef mach_error_t DAReturn;
 typedef const struct __DADissenter * DADissenterRef;
 extern DADissenterRef DADissenterCreate( CFAllocatorRef allocator, DAReturn status, CFStringRef string );
diff --git a/clang/test/Sema/shift.c b/clang/test/Sema/shift.c
index 4273cab98ee3..63c97fe7b029 100644
--- a/clang/test/Sema/shift.c
+++ b/clang/test/Sema/shift.c
@@ -1,7 +1,9 @@
-// RUN: %clang -Wall -ffreestanding -fsyntax-only -Xclang -verify %s
+// RUN: %clang -Wall -Wshift-sign-overflow -ffreestanding -fsyntax-only -Xclang -verify %s
 
 #include <limits.h>
 
+#define WORD_BIT (sizeof(int) * CHAR_BIT)
+
 enum {
   X = 1 << 0,
   Y = 1 << 1,
@@ -32,6 +34,22 @@ void test() {
   c <<= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
   c >>= CHAR_BIT+1; // expected-warning {{shift count >= width of type}}
   (void)((long)c << CHAR_BIT);
+
+  int i;
+  i = 1 << (WORD_BIT - 2);
+  i = 2 << (WORD_BIT - 1); // expected-warning {{the promoted type of the shift expression is 'int'}}
+  i = 1 << (WORD_BIT - 1); // expected-warning {{overrides the sign bit of the promoted type of the shift expression ('int')}}
+  i = -1 << (WORD_BIT - 1);
+  i = 0 << (WORD_BIT - 1);
+  i = (char)1 << (WORD_BIT - 2);
+
+  unsigned u;
+  u = 1U << (WORD_BIT - 1);
+  u = 5U << (WORD_BIT - 1);
+
+  long long int lli;
+  lli = INT_MIN << 2; // expected-warning {{the promoted type of the shift expression is 'int'}}
+  lli = 1LL << (sizeof(long long) * CHAR_BIT - 2);
 }
 
 #define a 0