Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -6175,8 +6175,11 @@
     break;
   case Intrinsic::log10:
     // log10(pow(10.0, x)) -> x
+    // log10(exp10(x)) -> x
     if (Q.CxtI->hasAllowReassoc() &&
-        match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), m_Value(X))))
+        (match(Op0, m_Intrinsic<Intrinsic::exp10>(m_Value(X))) ||
+         match(Op0,
+               m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0), m_Value(X)))))
       return X;
     break;
   case Intrinsic::experimental_vector_reverse:
Index: llvm/test/Transforms/InstSimplify/log-exp-intrinsic.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/log-exp-intrinsic.ll
+++ llvm/test/Transforms/InstSimplify/log-exp-intrinsic.ll
@@ -194,9 +194,7 @@
 
 define double @log10_reassoc_exp10_strict(double %a) {
 ; CHECK-LABEL: @log10_reassoc_exp10_strict(
-; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.exp10.f64(double [[A:%.*]])
-; CHECK-NEXT:    [[TMP2:%.*]] = call reassoc double @llvm.log10.f64(double [[TMP1]])
-; CHECK-NEXT:    ret double [[TMP2]]
+; CHECK-NEXT:    ret double [[A:%.*]]
 ;
   %1 = call double @llvm.exp10.f64(double %a)
   %2 = call reassoc double @llvm.log10.f64(double %1)
@@ -231,11 +229,7 @@
 
 define double @log10_exp10_log10_exp10_reassoc(double %a) {
 ; CHECK-LABEL: @log10_exp10_log10_exp10_reassoc(
-; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.exp10.f64(double [[A:%.*]])
-; CHECK-NEXT:    [[TMP2:%.*]] = call reassoc double @llvm.log10.f64(double [[TMP1]])
-; CHECK-NEXT:    [[TMP3:%.*]] = call double @llvm.exp10.f64(double [[TMP2]])
-; CHECK-NEXT:    [[TMP4:%.*]] = call reassoc double @llvm.log10.f64(double [[TMP3]])
-; CHECK-NEXT:    ret double [[TMP4]]
+; CHECK-NEXT:    ret double [[A:%.*]]
 ;
   %1 = call double @llvm.exp10.f64(double %a)
   %2 = call reassoc double @llvm.log10.f64(double %1)