diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2258,14 +2258,26 @@
       return II;
     }
 
-    // Try to simplify the underlying FMul.
-    if (Value *V = SimplifyFMulInst(II->getArgOperand(0), II->getArgOperand(1),
-                                    II->getFastMathFlags(),
-                                    SQ.getWithInstruction(II))) {
-      auto *FAdd = BinaryOperator::CreateFAdd(V, II->getArgOperand(2));
-      FAdd->copyFastMathFlags(II);
-      return FAdd;
-    }
+    // Try to simplify the underlying FMul to a value that does not require
+    // additional rounding. SimplifyFMulInst will either simplify to an existing
+    // value or constant fold the multiply. If simplified to an existing value,
+    // no additional rounding is required. Constant folding could introduce
+    // additional rounding. We only try to simplify multiplications with 2
+    // constants, if either is 1.0 or 0.0, which won't required rounding.
+    // Fmuladd intrinsics do not make any guarantees about rounding, so we can
+    // constant fold arbirary multiplies.
+    if (match(Src0, m_FPOne()) || match(Src1, m_FPOne()) ||
+        match(Src0, m_Zero()) || match(Src1, m_Zero()) ||
+        !isa<Constant>(II->getArgOperand(0)) ||
+        !isa<Constant>(II->getArgOperand(1)) || IID == Intrinsic::fmuladd)
+      // Try to simplify the underlying FMul.
+      if (Value *V = SimplifyFMulInst(
+              II->getArgOperand(0), II->getArgOperand(1),
+              II->getFastMathFlags(), SQ.getWithInstruction(II))) {
+        auto *FAdd = BinaryOperator::CreateFAdd(V, II->getArgOperand(2));
+        FAdd->copyFastMathFlags(II);
+        return FAdd;
+      }
 
     break;
   }
diff --git a/llvm/test/Transforms/InstCombine/fma.ll b/llvm/test/Transforms/InstCombine/fma.ll
--- a/llvm/test/Transforms/InstCombine/fma.ll
+++ b/llvm/test/Transforms/InstCombine/fma.ll
@@ -445,6 +445,70 @@
   ret <2 x double> %res
 }
 
+; We do not fold constant multiplies in FMAs, as they could require rounding, unless either constant is 0.0 or 1.0.
+define <2 x double> @fma_const_fmul(<2 x double> %b) {
+; CHECK-LABEL: @fma_const_fmul(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RES:%.*]] = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 0x4131233302898702, double 0x40C387800000D6C0>, <2 x double> <double 1.291820e-08, double 9.123000e-06>, <2 x double> [[B:%.*]])
+; CHECK-NEXT:    ret <2 x double> [[RES]]
+;
+entry:
+  %res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 1123123.0099110012314, double 9999.0000001>, <2 x double> <double 0.0000000129182, double 0.000009123>, <2 x double> %b)
+  ret <2 x double> %res
+}
+
+define <2 x double> @fma_const_fmul_zero(<2 x double> %b) {
+; CHECK-LABEL: @fma_const_fmul_zero(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret <2 x double> [[B:%.*]]
+;
+entry:
+  %res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 0.0, double 0.0>, <2 x double> <double 1123123.0099110012314, double 9999.0000001>, <2 x double> %b)
+  ret <2 x double> %res
+}
+
+define <2 x double> @fma_const_fmul_zero2(<2 x double> %b) {
+; CHECK-LABEL: @fma_const_fmul_zero2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    ret <2 x double> [[B:%.*]]
+;
+entry:
+  %res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 1123123.0099110012314, double 9999.0000001>, <2 x double> <double 0.0, double 0.0>, <2 x double> %b)
+  ret <2 x double> %res
+}
+
+define <2 x double> @fma_const_fmul_one(<2 x double> %b) {
+; CHECK-LABEL: @fma_const_fmul_one(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RES:%.*]] = fadd nnan nsz <2 x double> [[B:%.*]], <double 0x4131233302898702, double 0x40C387800000D6C0>
+; CHECK-NEXT:    ret <2 x double> [[RES]]
+;
+entry:
+  %res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 1.0, double 1.0>, <2 x double> <double 1123123.0099110012314, double 9999.0000001>, <2 x double> %b)
+  ret <2 x double> %res
+}
+
+define <2 x double> @fma_const_fmul_one2(<2 x double> %b) {
+; CHECK-LABEL: @fma_const_fmul_one2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RES:%.*]] = fadd nnan nsz <2 x double> [[B:%.*]], <double 0x4131233302898702, double 0x40C387800000D6C0>
+; CHECK-NEXT:    ret <2 x double> [[RES]]
+;
+entry:
+  %res = call nnan nsz <2 x double> @llvm.fma.v2f64(<2 x double> <double 1123123.0099110012314, double 9999.0000001>, <2 x double> <double 1.0, double 1.0>, <2 x double> %b)
+  ret <2 x double> %res
+}
+
+define <2 x double> @fmuladd_const_fmul(<2 x double> %b) {
+; CHECK-LABEL: @fmuladd_const_fmul(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RES:%.*]] = fadd nnan nsz <2 x double> [[B:%.*]], <double 0x3F8DB6C076AD949B, double 0x3FB75A405B6E6D69>
+; CHECK-NEXT:    ret <2 x double> [[RES]]
+;
+entry:
+  %res = call nnan nsz <2 x double> @llvm.fmuladd.v2f64(<2 x double> <double 1123123.0099110012314, double 9999.0000001>, <2 x double> <double 0.0000000129182, double 0.000009123>, <2 x double> %b)
+  ret <2 x double> %res
+}
 
 declare <2 x double> @llvm.fma.v2f64(<2 x double>, <2 x double>, <2 x double>)
 declare <2 x double> @llvm.sqrt.v2f64(<2 x double>)