Index: lib/Transforms/InstCombine/InstCombineAddSub.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1631,6 +1631,11 @@
       return BinaryOperator::CreateAdd(Op0,
                                       Builder->CreateSub(Z, Y, Op1->getName()));
 
+    // (X + Y) - (X + Z) --> (Y - Z)
+    if (match(Op0, m_Add(m_Value(X), m_Value(Y))) &&
+        match(Op1, m_Add(m_Value(X), m_Value(Z))))
+      return BinaryOperator::CreateSub(Y, Z);
+
     // (X - (X & Y))   -->   (X & ~Y)
     //
     if (match(Op1, m_And(m_Value(Y), m_Specific(Op0))) ||
Index: test/Transforms/InstCombine/sub.ll
===================================================================
--- test/Transforms/InstCombine/sub.ll
+++ test/Transforms/InstCombine/sub.ll
@@ -529,3 +529,13 @@
 ; CHECK-NEXT: [[ADD:%.*]] = add nsw i32 %x, -32768
 ; CHECK: ret i32 [[ADD]]
 }
+
+define i32 @test45(i32 %x, i32 %y, i32 %z) {
+ %add = add i32 %x, %y
+ %add1 = add i32 %x, %z
+ %sub = sub i32 %add, %add1
+ ret i32 %sub
+; CHECK-LABEL: @test45(
+; CHECK-NEXT: %sub = sub i32 %y, %z
+; CHECK-NEXT: ret i32 %sub
+}