Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -5255,6 +5255,16 @@
   Type *ReturnType = F->getReturnType();
   unsigned BitWidth = ReturnType->getScalarSizeInBits();
   switch (IID) {
+  case Intrinsic::abs: {
+    // abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here.
+    // It is always ok to pick the earlier abs. We'll just lose nsw if its only
+    // on the outer abs.
+    if (auto *II = dyn_cast<IntrinsicInst>(Op0))
+      if (II->getIntrinsicID() == IID)
+        return II;
+
+    break;
+  }
   case Intrinsic::smax:
   case Intrinsic::smin:
   case Intrinsic::umax:
Index: llvm/test/Transforms/InstSimplify/call.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/call.ll
+++ llvm/test/Transforms/InstSimplify/call.ll
@@ -2,6 +2,48 @@
 ; RUN: opt < %s -instsimplify -S | FileCheck %s
 ; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
 
+declare i32 @llvm.abs.i32(i32, i1)
+
+define i32 @test_abs_abs_0(i32 %x) {
+; CHECK-LABEL: @test_abs_abs_0(
+; CHECK-NEXT:    [[A:%.*]] = call i32 @llvm.abs.i32(i32 [[X:%.*]], i1 false)
+; CHECK-NEXT:    ret i32 [[A]]
+;
+  %a = call i32 @llvm.abs.i32(i32 %x, i1 false)
+  %b = call i32 @llvm.abs.i32(i32 %a, i1 false)
+  ret i32 %b
+}
+
+define i32 @test_abs_abs_1(i32 %x) {
+; CHECK-LABEL: @test_abs_abs_1(
+; CHECK-NEXT:    [[A:%.*]] = call i32 @llvm.abs.i32(i32 [[X:%.*]], i1 true)
+; CHECK-NEXT:    ret i32 [[A]]
+;
+  %a = call i32 @llvm.abs.i32(i32 %x, i1 true)
+  %b = call i32 @llvm.abs.i32(i32 %a, i1 false)
+  ret i32 %b
+}
+
+define i32 @test_abs_abs_2(i32 %x) {
+; CHECK-LABEL: @test_abs_abs_2(
+; CHECK-NEXT:    [[A:%.*]] = call i32 @llvm.abs.i32(i32 [[X:%.*]], i1 false)
+; CHECK-NEXT:    ret i32 [[A]]
+;
+  %a = call i32 @llvm.abs.i32(i32 %x, i1 false)
+  %b = call i32 @llvm.abs.i32(i32 %a, i1 true)
+  ret i32 %b
+}
+
+define i32 @test_abs_abs_3(i32 %x) {
+; CHECK-LABEL: @test_abs_abs_3(
+; CHECK-NEXT:    [[A:%.*]] = call i32 @llvm.abs.i32(i32 [[X:%.*]], i1 true)
+; CHECK-NEXT:    ret i32 [[A]]
+;
+  %a = call i32 @llvm.abs.i32(i32 %x, i1 true)
+  %b = call i32 @llvm.abs.i32(i32 %a, i1 true)
+  ret i32 %b
+}
+
 declare {i8, i1} @llvm.uadd.with.overflow.i8(i8 %a, i8 %b)
 declare {i8, i1} @llvm.sadd.with.overflow.i8(i8 %a, i8 %b)
 declare {i8, i1} @llvm.usub.with.overflow.i8(i8 %a, i8 %b)