diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -5987,6 +5987,11 @@
 
   SDLoc DL(Op);
 
+  // Because getNegatedExpression can delete nodes we need a handle to keep
+  // temporary nodes alive in case the recursion manages to create an identical
+  // node.
+  std::list<HandleSDNode> Handles;
+
   switch (Opcode) {
   case ISD::ConstantFP: {
     // Don't invert constant FP values after legalization unless the target says
@@ -6055,11 +6060,18 @@
     NegatibleCost CostX = NegatibleCost::Expensive;
     SDValue NegX =
         getNegatedExpression(X, DAG, LegalOps, OptForSize, CostX, Depth);
+    // Prevent this node from being deleted by the next call.
+    if (NegX)
+      Handles.emplace_back(NegX);
+
     // fold (fneg (fadd X, Y)) -> (fsub (fneg Y), X)
     NegatibleCost CostY = NegatibleCost::Expensive;
     SDValue NegY =
         getNegatedExpression(Y, DAG, LegalOps, OptForSize, CostY, Depth);
 
+    // We're done with the handles.
+    Handles.clear();
+
     // Negate the X if its cost is less or equal than Y.
     if (NegX && (CostX <= CostY)) {
       Cost = CostX;
@@ -6104,11 +6116,18 @@
     NegatibleCost CostX = NegatibleCost::Expensive;
     SDValue NegX =
         getNegatedExpression(X, DAG, LegalOps, OptForSize, CostX, Depth);
+    // Prevent this node from being deleted by the next call.
+    if (NegX)
+      Handles.emplace_back(NegX);
+
     // fold (fneg (fmul X, Y)) -> (fmul X, (fneg Y))
     NegatibleCost CostY = NegatibleCost::Expensive;
     SDValue NegY =
         getNegatedExpression(Y, DAG, LegalOps, OptForSize, CostY, Depth);
 
+    // We're done with the handles.
+    Handles.clear();
+
     // Negate the X if its cost is less or equal than Y.
     if (NegX && (CostX <= CostY)) {
       Cost = CostX;
@@ -6146,15 +6165,25 @@
     if (!NegZ)
       break;
 
+    // Prevent this node from being deleted by the next two calls.
+    Handles.emplace_back(NegZ);
+
     // fold (fneg (fma X, Y, Z)) -> (fma (fneg X), Y, (fneg Z))
     NegatibleCost CostX = NegatibleCost::Expensive;
     SDValue NegX =
         getNegatedExpression(X, DAG, LegalOps, OptForSize, CostX, Depth);
+    // Prevent this node from being deleted by the next call.
+    if (NegX)
+      Handles.emplace_back(NegX);
+
     // fold (fneg (fma X, Y, Z)) -> (fma X, (fneg Y), (fneg Z))
     NegatibleCost CostY = NegatibleCost::Expensive;
     SDValue NegY =
         getNegatedExpression(Y, DAG, LegalOps, OptForSize, CostY, Depth);
 
+    // We're done with the handles.
+    Handles.clear();
+
     // Negate the X if its cost is less or equal than Y.
     if (NegX && (CostX <= CostY)) {
       Cost = std::min(CostX, CostZ);
diff --git a/llvm/test/CodeGen/X86/pr49393.ll b/llvm/test/CodeGen/X86/pr49393.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/pr49393.ll
@@ -0,0 +1,55 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+define void @f() {
+; CHECK-LABEL: f:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    .p2align 4, 0x90
+; CHECK-NEXT:  .LBB0_1: # %for.cond
+; CHECK-NEXT:    # =>This Inner Loop Header: Depth=1
+; CHECK-NEXT:    imull %eax, %eax
+; CHECK-NEXT:    movsd {{.*#+}} xmm0 = mem[0],zero
+; CHECK-NEXT:    movapd %xmm0, %xmm1
+; CHECK-NEXT:    mulsd %xmm0, %xmm1
+; CHECK-NEXT:    subsd %xmm0, %xmm1
+; CHECK-NEXT:    cwtl
+; CHECK-NEXT:    xorps %xmm2, %xmm2
+; CHECK-NEXT:    cvtsi2sd %eax, %xmm2
+; CHECK-NEXT:    mulsd %xmm0, %xmm2
+; CHECK-NEXT:    mulsd %xmm0, %xmm2
+; CHECK-NEXT:    movapd %xmm2, %xmm3
+; CHECK-NEXT:    mulsd %xmm1, %xmm3
+; CHECK-NEXT:    mulsd %xmm0, %xmm2
+; CHECK-NEXT:    subsd %xmm3, %xmm1
+; CHECK-NEXT:    addsd %xmm2, %xmm1
+; CHECK-NEXT:    cvttsd2si %xmm1, %eax
+; CHECK-NEXT:    jmp .LBB0_1
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.cond, %entry
+  %b.0 = phi i16 [ 0, %entry ], [ %conv77, %for.cond ]
+  %mul18 = mul i16 %b.0, %b.0
+  %arrayidx.real = load double, double* undef, align 1
+  %arrayidx.imag = load double, double* undef, align 1
+  %mul_ac = fmul fast double %arrayidx.real, %arrayidx.real
+  %0 = fadd fast double 0.000000e+00, %arrayidx.real
+  %sub.r = fsub fast double %mul_ac, %0
+  %sub.i = fsub fast double 0.000000e+00, %arrayidx.imag
+  %conv28 = sitofp i16 %mul18 to double
+  %mul_bc32 = fmul fast double %arrayidx.imag, %conv28
+  %mul_bd46 = fmul fast double %mul_bc32, %arrayidx.imag
+  %mul_r49 = fsub fast double 0.000000e+00, %mul_bd46
+  %mul_ac59 = fmul fast double %mul_r49, %sub.r
+  %mul_bc48 = fmul fast double %mul_bc32, %arrayidx.real
+  %mul_i50 = fadd fast double 0.000000e+00, %mul_bc48
+  %1 = fmul fast double %mul_i50, %sub.i
+  %.neg = fneg fast double %0
+  %.neg19 = fmul fast double %1, -1.000000e+00
+  %.neg20 = fadd fast double %.neg, %mul_ac
+  %2 = fadd fast double %.neg20, %mul_ac59
+  %sub.r75 = fadd fast double %2, %.neg19
+  %conv77 = fptosi double %sub.r75 to i16
+  br label %for.cond
+}