diff --git a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -1367,6 +1367,14 @@
   return nullptr;
 }
 
+bool phiAllConstantOperandsAreZero(PHINode &PN) {
+  size_t ZeroConstCount = 0;
+  for (Value *V : PN.operands())
+    if (Constant *ConstVA = dyn_cast<Constant>(V))
+      if (ConstVA->isZeroValue())
+        ZeroConstCount += 1;
+  return ZeroConstCount == PN.getNumOperands() - 1;
+}
 // PHINode simplification
 //
 Instruction *InstCombinerImpl::visitPHINode(PHINode &PN) {
@@ -1465,6 +1473,23 @@
         return &PN;
     }
   }
+  if (phiAllConstantOperandsAreZero(PN)) {
+    for (Value *Operands : PN.operands()) {
+      if (Instruction *Fmul = dyn_cast<Instruction>(Operands)) {
+        if (Fmul->getOpcode() != Instruction::FMul || !Fmul->hasNoInfs() ||
+            !Fmul->hasNoNaNs() || !Fmul->hasNoSignedZeros())
+          break;
+        for (Value *InstOperand : Fmul->operands()) {
+          if (PHINode *PhiOperand = dyn_cast<PHINode>(InstOperand)) {
+            if (PhiOperand != &PN)
+              continue;
+            auto *ZeroVal = Constant::getNullValue(PN.getType());
+            replaceInstUsesWith(PN, ZeroVal);
+          }
+        }
+      }
+    }
+  }
 
   // We sometimes end up with phi cycles that non-obviously end up being the
   // same value, for example:
diff --git a/llvm/test/Transforms/InstCombine/remove-loop-phi-fastmul.ll b/llvm/test/Transforms/InstCombine/remove-loop-phi-fastmul.ll
--- a/llvm/test/Transforms/InstCombine/remove-loop-phi-fastmul.ll
+++ b/llvm/test/Transforms/InstCombine/remove-loop-phi-fastmul.ll
@@ -3,19 +3,14 @@
 define double @test_mul_fast_flags() {
 ; CHECK-LABEL: @test_mul_fast_flags(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[ARR_D:%.*]] = alloca [1000 x double], align 8
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[I_02:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_BODY]] ]
-; CHECK-NEXT:    [[F_PROD_01:%.*]] = phi double [ 0.000000e+00, [[ENTRY]] ], [ [[MUL:%.*]], [[FOR_BODY]] ]
-; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [1000 x double], ptr [[ARR_D]], i64 0, i64 [[I_02]]
-; CHECK-NEXT:    [[TMP0:%.*]] = load double, ptr [[ARRAYIDX]], align 8
-; CHECK-NEXT:    [[MUL]] = fmul fast double [[F_PROD_01]], [[TMP0]]
 ; CHECK-NEXT:    [[INC]] = add i64 [[I_02]], 1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[INC]], 1000
 ; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[END:%.*]]
 ; CHECK:       end:
-; CHECK-NEXT:    ret double [[MUL]]
+; CHECK-NEXT:    ret double 0.000000e+00
 ;
 entry:
   %arr_d = alloca [1000 x double], align 8
@@ -147,19 +142,14 @@
 define double @test_phi_non_constant_operand() {
 ; CHECK-LABEL: @test_phi_non_constant_operand(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[ARR_D:%.*]] = alloca [1000 x double], align 8
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[I_02:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[FOR_BODY]] ]
-; CHECK-NEXT:    [[F_PROD_01:%.*]] = phi double [ 0.000000e+00, [[ENTRY]] ], [ [[MUL:%.*]], [[FOR_BODY]] ]
-; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [1000 x double], ptr [[ARR_D]], i64 0, i64 [[I_02]]
-; CHECK-NEXT:    [[TMP0:%.*]] = load double, ptr [[ARRAYIDX]], align 8
-; CHECK-NEXT:    [[MUL]] = fmul fast double [[F_PROD_01]], [[TMP0]]
 ; CHECK-NEXT:    [[INC]] = add i64 [[I_02]], 1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[INC]], 1000
 ; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[END:%.*]]
 ; CHECK:       end:
-; CHECK-NEXT:    ret double [[MUL]]
+; CHECK-NEXT:    ret double 0.000000e+00
 ;
 entry:
   %arr_d = alloca [1000 x double], align 8
@@ -220,21 +210,16 @@
 define double @test_multiple_phi_operands() {
 ; CHECK-LABEL: @test_multiple_phi_operands(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[ARR_D:%.*]] = alloca [1000 x double], align 8
 ; CHECK-NEXT:    br i1 false, label [[FOR_BODY:%.*]], label [[ENTRY_2:%.*]]
 ; CHECK:       entry_2:
 ; CHECK-NEXT:    br label [[FOR_BODY]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[I_02:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ 0, [[ENTRY_2]] ], [ [[INC:%.*]], [[FOR_BODY]] ]
-; CHECK-NEXT:    [[F_PROD_01:%.*]] = phi double [ 0.000000e+00, [[ENTRY]] ], [ 0.000000e+00, [[ENTRY_2]] ], [ [[MUL:%.*]], [[FOR_BODY]] ]
-; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds [1000 x double], ptr [[ARR_D]], i64 0, i64 [[I_02]]
-; CHECK-NEXT:    [[TMP0:%.*]] = load double, ptr [[ARRAYIDX]], align 8
-; CHECK-NEXT:    [[MUL]] = fmul fast double [[F_PROD_01]], [[TMP0]]
 ; CHECK-NEXT:    [[INC]] = add i64 [[I_02]], 1
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[INC]], 1000
 ; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[END:%.*]]
 ; CHECK:       end:
-; CHECK-NEXT:    ret double [[MUL]]
+; CHECK-NEXT:    ret double 0.000000e+00
 ;
 entry:
   %arr_d = alloca [1000 x double], align 8