diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -3217,14 +3217,25 @@
   case ISD::FCOPYSIGN:
     Results.push_back(ExpandFCOPYSIGN(Node));
     break;
-  case ISD::FNEG:
-    // Expand Y = FNEG(X) ->  Y = SUB -0.0, X
-    Tmp1 = DAG.getConstantFP(-0.0, dl, Node->getValueType(0));
-    // TODO: If FNEG has fast-math-flags, propagate them to the FSUB.
-    Tmp1 = DAG.getNode(ISD::FSUB, dl, Node->getValueType(0), Tmp1,
-                       Node->getOperand(0));
-    Results.push_back(Tmp1);
+  case ISD::FNEG: {
+    // Expand using integer operations. (We used to expand to FSUB, but that's
+    // not correct in cases involving NaNs.)
+    SDLoc DL(Node);
+
+    // Get the sign bit as an integer.
+    FloatSignAsInt SignAsInt;
+    getSignAsIntValue(SignAsInt, DL, Node->getOperand(0));
+    EVT IntVT = SignAsInt.IntValue.getValueType();
+
+    // Flip the sign.
+    SDValue SignMask = DAG.getConstant(SignAsInt.SignMask, DL, IntVT);
+    SDValue SignFlip = DAG.getNode(ISD::XOR, DL, IntVT, SignAsInt.IntValue,
+                                   SignMask);
+
+    // Convert back to float.
+    Results.push_back(modifySignAsInt(SignAsInt, DL, SignFlip));
     break;
+  }
   case ISD::FABS:
     Results.push_back(ExpandFABS(Node));
     break;
diff --git a/llvm/test/CodeGen/AArch64/arm64-fp128.ll b/llvm/test/CodeGen/AArch64/arm64-fp128.ll
--- a/llvm/test/CodeGen/AArch64/arm64-fp128.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-fp128.ll
@@ -262,19 +262,17 @@
 }
 
 define fp128 @test_neg(fp128 %in) {
-; CHECK: [[$MINUS0:.LCPI[0-9]+_0]]:
-; Make sure the weird hex constant below *is* -0.0
-; CHECK-NEXT: fp128 -0
-
 ; CHECK-LABEL: test_neg:
 
-  ; Could in principle be optimized to fneg which we can't select, this makes
-  ; sure that doesn't happen.
+;; We convert this to fneg, and target-independent code expands it with
+;; integer operations.
   %ret = fsub fp128 0xL00000000000000008000000000000000, %in
-; CHECK: mov v1.16b, v0.16b
-; CHECK: ldr q0, [{{x[0-9]+}}, :lo12:[[$MINUS0]]]
-; CHECK: bl __subtf3
-
   ret fp128 %ret
-; CHECK: ret
+
+; CHECK:      str q0, [sp, #-16]!
+; CHECK-NEXT: ldrb w8, [sp, #15]
+; CHECK-NEXT: eor w8, w8, #0x80
+; CHECK-NEXT: strb w8, [sp, #15]
+; CHECK-NEXT: ldr q0, [sp], #16
+; CHECK-NEXT: ret
 }
diff --git a/llvm/test/CodeGen/Thumb2/mve-fp-negabs.ll b/llvm/test/CodeGen/Thumb2/mve-fp-negabs.ll
--- a/llvm/test/CodeGen/Thumb2/mve-fp-negabs.ll
+++ b/llvm/test/CodeGen/Thumb2/mve-fp-negabs.ll
@@ -67,31 +67,20 @@
 define arm_aapcs_vfpcc <2 x double> @fneg_float64_t(<2 x double> %src) {
 ; CHECK-LABEL: fneg_float64_t:
 ; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    .save {r4, r5, r7, lr}
-; CHECK-NEXT:    push {r4, r5, r7, lr}
-; CHECK-NEXT:    .vsave {d8, d9}
-; CHECK-NEXT:    vpush {d8, d9}
-; CHECK-NEXT:    vmov q4, q0
-; CHECK-NEXT:    vldr d0, .LCPI2_0
-; CHECK-NEXT:    vmov r2, r3, d9
-; CHECK-NEXT:    vmov r4, r5, d0
-; CHECK-NEXT:    mov r0, r4
-; CHECK-NEXT:    mov r1, r5
-; CHECK-NEXT:    bl __aeabi_dsub
-; CHECK-NEXT:    vmov r2, r3, d8
-; CHECK-NEXT:    vmov d9, r0, r1
-; CHECK-NEXT:    mov r0, r4
-; CHECK-NEXT:    mov r1, r5
-; CHECK-NEXT:    bl __aeabi_dsub
-; CHECK-NEXT:    vmov d8, r0, r1
-; CHECK-NEXT:    vmov q0, q4
-; CHECK-NEXT:    vpop {d8, d9}
-; CHECK-NEXT:    pop {r4, r5, r7, pc}
-; CHECK-NEXT:    .p2align 3
-; CHECK-NEXT:  @ %bb.1:
-; CHECK-NEXT:  .LCPI2_0:
-; CHECK-NEXT:    .long 0 @ double -0
-; CHECK-NEXT:    .long 2147483648
+; CHECK-NEXT:    .pad #16
+; CHECK-NEXT:    sub sp, #16
+; CHECK-NEXT:    vstr d1, [sp]
+; CHECK-NEXT:    ldrb.w r0, [sp, #7]
+; CHECK-NEXT:    vstr d0, [sp, #8]
+; CHECK-NEXT:    ldrb.w r1, [sp, #15]
+; CHECK-NEXT:    eor r0, r0, #128
+; CHECK-NEXT:    strb.w r0, [sp, #7]
+; CHECK-NEXT:    vldr d1, [sp]
+; CHECK-NEXT:    eor r0, r1, #128
+; CHECK-NEXT:    strb.w r0, [sp, #15]
+; CHECK-NEXT:    vldr d0, [sp, #8]
+; CHECK-NEXT:    add sp, #16
+; CHECK-NEXT:    bx lr
 entry:
   %0 = fsub nnan ninf nsz <2 x double> <double 0.0e0, double 0.0e0>, %src
   ret <2 x double> %0