Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -74,11 +74,12 @@
 //   b)  (x & (~(-1 << MaskShAmt))) << ShiftShAmt
 //   c)  (x & (-1 >> MaskShAmt)) << ShiftShAmt
 //   d)  (x & ((-1 << MaskShAmt) >> MaskShAmt)) << ShiftShAmt
+//   e)  ((x << MaskShAmt) l>> MaskShAmt) << ShiftShAmt
 // All these patterns can be simplified to just:
 //   x << ShiftShAmt
 // iff:
-//   a,b) (MaskShAmt+ShiftShAmt) u>= bitwidth(x)
-//   c,d) (ShiftShAmt-MaskShAmt) s>= 0 (i.e. ShiftShAmt u>= MaskShAmt)
+//   a,b)   (MaskShAmt+ShiftShAmt) u>= bitwidth(x)
+//   c,d,e) (ShiftShAmt-MaskShAmt) s>= 0 (i.e. ShiftShAmt u>= MaskShAmt)
 static Instruction *
 dropRedundantMaskingOfLeftShiftInput(BinaryOperator *OuterShift,
                                      const SimplifyQuery &SQ) {
@@ -115,7 +116,9 @@
                                                APInt(BitWidth, BitWidth))))
       return nullptr;
     // All good, we can do this fold.
-  } else if (match(Masked, m_c_And(m_CombineOr(MaskC, MaskD), m_Value(X)))) {
+  } else if (match(Masked, m_c_And(m_CombineOr(MaskC, MaskD), m_Value(X))) ||
+             match(Masked, m_LShr(m_Shl(m_Value(X), m_Value(MaskShAmt)),
+                                  m_Deferred(MaskShAmt)))) {
     // Can we simplify (ShiftShAmt-MaskShAmt) ?
     Value *ShAmtsDiff =
         SimplifySubInst(ShiftShAmt, MaskShAmt, /*IsNSW=*/false, /*IsNUW=*/false,
Index: llvm/trunk/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-e.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-e.ll
+++ llvm/trunk/test/Transforms/InstCombine/redundant-left-shift-input-masking-variant-e.ll
@@ -21,7 +21,7 @@
 ; CHECK-NEXT:    [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
 ; CHECK-NEXT:    call void @use32(i32 [[T0]])
 ; CHECK-NEXT:    call void @use32(i32 [[T1]])
-; CHECK-NEXT:    [[T2:%.*]] = shl i32 [[T1]], [[NBITS]]
+; CHECK-NEXT:    [[T2:%.*]] = shl i32 [[X]], [[NBITS]]
 ; CHECK-NEXT:    ret i32 [[T2]]
 ;
   %t0 = shl i32 %x, %nbits
@@ -40,7 +40,7 @@
 ; CHECK-NEXT:    call void @use32(i32 [[T0]])
 ; CHECK-NEXT:    call void @use32(i32 [[T1]])
 ; CHECK-NEXT:    call void @use32(i32 [[T2]])
-; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[T1]], [[T2]]
+; CHECK-NEXT:    [[T3:%.*]] = shl i32 [[X]], [[T2]]
 ; CHECK-NEXT:    ret i32 [[T3]]
 ;
   %t0 = shl i32 %x, %nbits
@@ -65,7 +65,7 @@
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T0]])
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T1]])
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T2]])
-; CHECK-NEXT:    [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT:    [[T3:%.*]] = shl <3 x i32> [[X]], [[T2]]
 ; CHECK-NEXT:    ret <3 x i32> [[T3]]
 ;
   %t0 = shl <3 x i32> %x, %nbits
@@ -86,7 +86,7 @@
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T0]])
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T1]])
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T2]])
-; CHECK-NEXT:    [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT:    [[T3:%.*]] = shl <3 x i32> [[X]], [[T2]]
 ; CHECK-NEXT:    ret <3 x i32> [[T3]]
 ;
   %t0 = shl <3 x i32> %x, %nbits
@@ -107,7 +107,7 @@
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T0]])
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T1]])
 ; CHECK-NEXT:    call void @use3xi32(<3 x i32> [[T2]])
-; CHECK-NEXT:    [[T3:%.*]] = shl <3 x i32> [[T1]], [[T2]]
+; CHECK-NEXT:    [[T3:%.*]] = shl <3 x i32> [[X]], [[T2]]
 ; CHECK-NEXT:    ret <3 x i32> [[T3]]
 ;
   %t0 = shl <3 x i32> %x, %nbits
@@ -128,7 +128,7 @@
 ; CHECK-NEXT:    [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
 ; CHECK-NEXT:    call void @use32(i32 [[T0]])
 ; CHECK-NEXT:    call void @use32(i32 [[T1]])
-; CHECK-NEXT:    [[T2:%.*]] = shl nuw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT:    [[T2:%.*]] = shl i32 [[X]], [[NBITS]]
 ; CHECK-NEXT:    ret i32 [[T2]]
 ;
   %t0 = shl i32 %x, %nbits
@@ -145,7 +145,7 @@
 ; CHECK-NEXT:    [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
 ; CHECK-NEXT:    call void @use32(i32 [[T0]])
 ; CHECK-NEXT:    call void @use32(i32 [[T1]])
-; CHECK-NEXT:    [[T2:%.*]] = shl nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT:    [[T2:%.*]] = shl i32 [[X]], [[NBITS]]
 ; CHECK-NEXT:    ret i32 [[T2]]
 ;
   %t0 = shl i32 %x, %nbits
@@ -162,7 +162,7 @@
 ; CHECK-NEXT:    [[T1:%.*]] = lshr i32 [[T0]], [[NBITS]]
 ; CHECK-NEXT:    call void @use32(i32 [[T0]])
 ; CHECK-NEXT:    call void @use32(i32 [[T1]])
-; CHECK-NEXT:    [[T2:%.*]] = shl nuw nsw i32 [[T1]], [[NBITS]]
+; CHECK-NEXT:    [[T2:%.*]] = shl i32 [[X]], [[NBITS]]
 ; CHECK-NEXT:    ret i32 [[T2]]
 ;
   %t0 = shl i32 %x, %nbits