Index: llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -564,6 +564,16 @@
         return replaceInstUsesWith(I, NewPow);
       }
 
+      // powi(x, y) * powi(x, z) -> powi(x, y + z)
+      if (match(Op0, m_Intrinsic<Intrinsic::powi>(m_Value(X), m_Value(Y))) &&
+          match(Op1, m_Intrinsic<Intrinsic::powi>(m_Specific(X), m_Value(Z)))) {
+        auto *YZ = Builder.CreateAdd(Y, Z);
+        Function *F = Intrinsic::getDeclaration(I.getModule(), Intrinsic::powi,
+                                                {X->getType(), YZ->getType()});
+        auto *NewPow = Builder.CreateCall(F, {X, YZ});
+        return replaceInstUsesWith(I, NewPow);
+      }
+
       // exp(X) * exp(Y) -> exp(X + Y)
       if (match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X))) &&
           match(Op1, m_Intrinsic<Intrinsic::exp>(m_Value(Y)))) {
Index: llvm/test/Transforms/InstCombine/powi.ll
===================================================================
--- llvm/test/Transforms/InstCombine/powi.ll
+++ llvm/test/Transforms/InstCombine/powi.ll
@@ -4,6 +4,7 @@
 declare double @llvm.powi.f64.i32(double, i32)
 declare double @llvm.fabs.f64(double)
 declare double @llvm.copysign.f64(double, double)
+declare void @use(double)
 
 define double @powi_fneg_even_int(double %x) {
 ; CHECK-LABEL: @powi_fneg_even_int(
@@ -79,3 +80,138 @@
   %r = tail call double @llvm.powi.f64.i32(double %cs, i32 5)
   ret double %r
 }
+
+define double @powi_fmul_arg0_no_reassoc(double %x, i32 %i) {
+; CHECK-LABEL: @powi_fmul_arg0_no_reassoc(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[POW:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[I:%.*]])
+; CHECK-NEXT:    [[MUL:%.*]] = fmul double [[POW]], [[X]]
+; CHECK-NEXT:    ret double [[MUL]]
+;
+entry:
+  %pow = tail call double @llvm.powi.f64.i32(double %x, i32 %i)
+  %mul = fmul double %pow, %x
+  ret double %mul
+}
+
+
+define double @powi_fmul_arg0(double %x, i32 %i) {
+; CHECK-LABEL: @powi_fmul_arg0(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[POW:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[I:%.*]])
+; CHECK-NEXT:    [[MUL:%.*]] = fmul reassoc double [[POW]], [[X]]
+; CHECK-NEXT:    ret double [[MUL]]
+;
+entry:
+  %pow = tail call double @llvm.powi.f64.i32(double %x, i32 %i)
+  %mul = fmul reassoc double %pow, %x
+  ret double %mul
+}
+
+define double @powi_fmul_arg0_use(double %x, i32 %i) {
+; CHECK-LABEL: @powi_fmul_arg0_use(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[POW:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[I:%.*]])
+; CHECK-NEXT:    tail call void @use(double [[POW]])
+; CHECK-NEXT:    [[MUL:%.*]] = fmul reassoc double [[POW]], [[X]]
+; CHECK-NEXT:    ret double [[MUL]]
+;
+entry:
+  %pow = tail call double @llvm.powi.f64.i32(double %x, i32 %i)
+  tail call void @use(double %pow)
+  %mul = fmul reassoc double %pow, %x
+  ret double %mul
+}
+
+define double @powi_fmul_powi_no_reassoc(double %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @powi_fmul_powi_no_reassoc(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Y:%.*]])
+; CHECK-NEXT:    [[P2:%.*]] = tail call double @llvm.powi.f64.i32(double [[X]], i32 [[Z:%.*]])
+; CHECK-NEXT:    [[MUL:%.*]] = fmul double [[P2]], [[P1]]
+; CHECK-NEXT:    ret double [[MUL]]
+;
+entry:
+  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %z)
+  %mul = fmul double %p2, %p1
+  ret double %mul
+}
+
+
+define double @powi_fmul_powi(double %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @powi_fmul_powi(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[Z:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[TMP0]])
+; CHECK-NEXT:    ret double [[TMP1]]
+;
+entry:
+  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %z)
+  %mul = fmul reassoc double %p2, %p1
+  ret double %mul
+}
+
+define double @powi_fmul_powi_same_power(double %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @powi_fmul_powi_same_power(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = shl i32 [[Y:%.*]], 1
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[TMP0]])
+; CHECK-NEXT:    ret double [[TMP1]]
+;
+entry:
+  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %mul = fmul reassoc double %p2, %p1
+  ret double %mul
+}
+
+define double @powi_fmul_powi_use_first(double %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @powi_fmul_powi_use_first(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Y:%.*]])
+; CHECK-NEXT:    tail call void @use(double [[P1]])
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[Z:%.*]], [[Y]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.powi.f64.i32(double [[X]], i32 [[TMP0]])
+; CHECK-NEXT:    ret double [[TMP1]]
+;
+entry:
+  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  tail call void @use(double %p1)
+  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %z)
+  %mul = fmul reassoc double %p2, %p1
+  ret double %mul
+}
+
+define double @powi_fmul_powi_use_second(double %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @powi_fmul_powi_use_second(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Z:%.*]])
+; CHECK-NEXT:    tail call void @use(double [[P1]])
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[Y:%.*]], [[Z]]
+; CHECK-NEXT:    [[TMP1:%.*]] = call double @llvm.powi.f64.i32(double [[X]], i32 [[TMP0]])
+; CHECK-NEXT:    ret double [[TMP1]]
+;
+entry:
+  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %z)
+  tail call void @use(double %p1)
+  %p2 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %mul = fmul reassoc double %p2, %p1
+  ret double %mul
+}
+
+define double @powi_fmul_different_base(double %x, double %m, i32 %y, i32 %z) {
+; CHECK-LABEL: @powi_fmul_different_base(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 [[Y:%.*]])
+; CHECK-NEXT:    [[P2:%.*]] = tail call double @llvm.powi.f64.i32(double [[M:%.*]], i32 [[Z:%.*]])
+; CHECK-NEXT:    [[MUL:%.*]] = fmul reassoc double [[P2]], [[P1]]
+; CHECK-NEXT:    ret double [[MUL]]
+;
+entry:
+  %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 %y)
+  %p2 = tail call double @llvm.powi.f64.i32(double %m, i32 %z)
+  %mul = fmul reassoc double %p2, %p1
+  ret double %mul
+}