diff --git a/llvm/lib/Target/X86/X86FloatingPoint.cpp b/llvm/lib/Target/X86/X86FloatingPoint.cpp
index 1e18a6769c940..d7f4eba62995a 100644
--- a/llvm/lib/Target/X86/X86FloatingPoint.cpp
+++ b/llvm/lib/Target/X86/X86FloatingPoint.cpp
@@ -976,22 +976,24 @@ void FPS::shuffleStackTop(const unsigned char *FixStack,
 //===----------------------------------------------------------------------===//
 
 void FPS::handleCall(MachineBasicBlock::iterator &I) {
+  MachineInstr &MI = *I;
   unsigned STReturns = 0;
   const MachineFunction* MF = I->getParent()->getParent();
 
-  for (const auto &MO : I->operands()) {
-    if (!MO.isReg())
+  for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+    MachineOperand &Op = MI.getOperand(i);
+    if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
       continue;
 
-    unsigned R = MO.getReg() - X86::FP0;
+    assert(Op.isImplicit() && "Expected implicit def/use");
 
-    if (R < 8) {
-      if (MF->getFunction().getCallingConv() != CallingConv::X86_RegCall) {
-        assert(MO.isDef() && MO.isImplicit());
-      }
+    if (Op.isDef())
+      STReturns |= 1 << getFPReg(Op);
 
-      STReturns |= 1 << R;
-    }
+    // Remove the operand so that later passes don't see it.
+    MI.RemoveOperand(i);
+    --i;
+    --e;
   }
 
   unsigned N = countTrailingOnes(STReturns);
diff --git a/llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll b/llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll
index ef3e3398d8160..e832e42fea188 100644
--- a/llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll
+++ b/llvm/test/CodeGen/X86/avx512-regcall-NoMask.ll
@@ -1,8 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; FIXME: Fix machine verifier issues and remove -verify-machineinstrs=0. PR39437.
-; RUN: llc < %s -mtriple=i386-pc-win32       -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs=0  | FileCheck %s --check-prefix=X32
-; RUN: llc < %s -mtriple=x86_64-win32        -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs=0  | FileCheck %s --check-prefix=WIN64
-; RUN: llc < %s -mtriple=x86_64-linux-gnu    -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs=0  | FileCheck %s --check-prefix=LINUXOSX64
+; RUN: llc < %s -mtriple=i386-pc-win32       -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs  | FileCheck %s --check-prefix=X32
+; RUN: llc < %s -mtriple=x86_64-win32        -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs  | FileCheck %s --check-prefix=WIN64
+; RUN: llc < %s -mtriple=x86_64-linux-gnu    -mattr=+avx512f -mattr=+avx512vl -mattr=+avx512bw -mattr=+avx512dq -verify-machineinstrs  | FileCheck %s --check-prefix=LINUXOSX64
 
 ; Test regcall when receiving/returning i1
 define x86_regcallcc i1 @test_argReti1(i1 %a)  {
@@ -604,7 +603,6 @@ define x86_regcallcc double @test_CallargParamf80(x86_fp80 %a)  {
 ; X32-NEXT:    fadd %st, %st(0)
 ; X32-NEXT:    calll _test_argParamf80
 ; X32-NEXT:    vaddsd %xmm0, %xmm0, %xmm0
-; X32-NEXT:    fstp %st(0)
 ; X32-NEXT:    popl %esp
 ; X32-NEXT:    retl
 ;
@@ -616,7 +614,6 @@ define x86_regcallcc double @test_CallargParamf80(x86_fp80 %a)  {
 ; WIN64-NEXT:    fadd %st, %st(0)
 ; WIN64-NEXT:    callq test_argParamf80
 ; WIN64-NEXT:    vaddsd %xmm0, %xmm0, %xmm0
-; WIN64-NEXT:    fstp %st(0)
 ; WIN64-NEXT:    popq %rsp
 ; WIN64-NEXT:    retq
 ; WIN64-NEXT:    .seh_handlerdata
@@ -631,7 +628,6 @@ define x86_regcallcc double @test_CallargParamf80(x86_fp80 %a)  {
 ; LINUXOSX64-NEXT:    fadd %st, %st(0)
 ; LINUXOSX64-NEXT:    callq test_argParamf80
 ; LINUXOSX64-NEXT:    vaddsd %xmm0, %xmm0, %xmm0
-; LINUXOSX64-NEXT:    fstp %st(0)
 ; LINUXOSX64-NEXT:    popq %rsp
 ; LINUXOSX64-NEXT:    .cfi_def_cfa_offset 8
 ; LINUXOSX64-NEXT:    retq