Index: llvm/lib/Target/PowerPC/PPC.td
===================================================================
--- llvm/lib/Target/PowerPC/PPC.td
+++ llvm/lib/Target/PowerPC/PPC.td
@@ -207,6 +207,13 @@
                                                  "true",
                                                  "Vectors use two units">;
 
+
+def FeaturePredictableSelectIsExpensive :
+  SubtargetFeature<"predictable-select-expensive",
+                   "PredictableSelectIsExpensive",
+                   "true",
+                   "Prefer likely predicted branches over selects">;
+
 // Since new processors generally contain a superset of features of those that
 // came before them, the idea is to make implementations of new processors
 // less error prone and easier to read.
@@ -273,10 +280,14 @@
     !listconcat(P8InheritableFeatures, P8SpecificFeatures);
 
   // Power9
-  list<SubtargetFeature> P9AdditionalFeatures = [DirectivePwr9,
-                                                 FeatureP9Altivec,
-                                                 FeatureP9Vector,
-                                                 FeatureISA3_0];
+  list<SubtargetFeature> P9AdditionalFeatures =
+    [DirectivePwr9,
+     FeatureP9Altivec,
+     FeatureP9Vector,
+     FeatureISA3_0,
+     FeaturePredictableSelectIsExpensive
+     ];
+
   // Some features are unique to Power9 and there is no reason to assume
   // they will be part of any future CPUs. One example is the narrower
   // dispatch for vector operations than scalar ones. For the time being,
Index: llvm/lib/Target/PowerPC/PPCISelLowering.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -1256,6 +1256,10 @@
     MaxLoadsPerMemcmp = 8;
     MaxLoadsPerMemcmpOptSize = 4;
   }
+
+  // Select is more expensive than a branch if the feature
+  // FeaturePredictableSelectIsExpensive has been set.
+  PredictableSelectIsExpensive = Subtarget.isPredictableSelectIsExpensive();
 }
 
 /// getMaxByValAlign - Helper for getByValTypeAlignment to determine
Index: llvm/lib/Target/PowerPC/PPCSubtarget.h
===================================================================
--- llvm/lib/Target/PowerPC/PPCSubtarget.h
+++ llvm/lib/Target/PowerPC/PPCSubtarget.h
@@ -139,6 +139,7 @@
   bool VectorsUseTwoUnits;
   bool UsePPCPreRASchedStrategy;
   bool UsePPCPostRASchedStrategy;
+  bool PredictableSelectIsExpensive = false;
 
   POPCNTDKind HasPOPCNTD;
 
@@ -387,6 +388,10 @@
   }
 
   bool isXRaySupported() const override { return IsPPC64 && IsLittleEndian; }
+
+  bool isPredictableSelectIsExpensive() const {
+    return PredictableSelectIsExpensive;
+  }
 };
 } // End llvm namespace
 
Index: llvm/test/CodeGen/PowerPC/select-to-branch.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/select-to-branch.mir
@@ -0,0 +1,114 @@
+# RUN: llc -verify-machineinstrs -mcpu=pwr9 -mtriple powerpc64le-unknown-linux-gnu \
+# RUN:   -run-pass=codegenprepare -o - %s | FileCheck %s
+--- |
+  define i32 @weighted_select1(i32 %a, i32 %b) #0 {
+    %cmp = icmp ne i32 %a, 0
+    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !14
+    ret i32 %sel
+
+  ; If branch_weights > 99% or branch_weights < 1%, the select will be
+  ; converted to branch, here !14 = 99/100, !14 = 99%, so it will do nothing.
+  ; CHECK-LABEL: weighted_select1
+  ; CHECK:         %cmp = icmp ne i32 %a, 0
+  ; CHECK-NEXT:    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !14
+  ; CHECK-NEXT:    ret i32 %sel
+  }
+
+  define i32 @weighted_select2(i32 %a, i32 %b) #0 {
+    %cmp = icmp ne i32 %a, 0
+    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
+    ret i32 %sel
+
+  ; If branch_weights > 99% or branch_weights < 1%, the select will be converted
+  ; to branch, here !15 = 100/101, !15 > 99%, so it will convert select to
+  ; branch.
+  ; CHECK-LABEL: weighted_select2
+  ; CHECK:         %cmp = icmp ne i32 %a, 0
+  ; CHECK-NEXT:    br i1 %cmp, label %select.end, label %select.false, !prof !15
+  ; CHECK:       select.false:
+  ; CHECK-NEXT:    br label %select.end
+  ; CHECK:       select.end:
+  ; CHECK-NEXT:    %sel = phi i32 [ %a, %0 ], [ %b, %select.false ]
+  ; CHECK-NEXT:    ret i32 %sel
+  }
+
+  define i32 @weighted_select3(i32 %a, i32 %b) #0 {
+    %cmp = icmp ne i32 %a, 0
+    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !16
+    ret i32 %sel
+
+  ; If branch_weights > 99% or branch_weights < 1%, the select will be converted
+  ; to branch, here !16 = 1/101, !16 < 1%, so it will convert select to branch.
+  ; CHECK-LABEL: weighted_select3
+  ; CHECK:         %cmp = icmp ne i32 %a, 0
+  ; CHECK-NEXT:    br i1 %cmp, label %select.end, label %select.false, !prof !16
+  ; CHECK:       select.false:
+  ; CHECK-NEXT:    br label %select.end
+  ; CHECK:       select.end:
+  ; CHECK-NEXT:    %sel = phi i32 [ %a, %0 ], [ %b, %select.false ]
+  ; CHECK-NEXT:    ret i32 %sel
+  }
+
+  define i32 @unweighted_select(i32 %a, i32 %b) #0 {
+    %cmp = icmp ne i32 %a, 0
+    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !17
+    ret i32 %sel
+
+  ; There is no weight_branch information, so it will do nothing.
+  ; CHECK-LABEL: unweighted_select
+  ; CHECK:         %cmp = icmp ne i32 %a, 0
+  ; CHECK-NEXT:    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !17
+  ; CHECK-NEXT:    ret i32 %sel
+  }
+
+  ; Function Attrs: optsize
+  define i32 @weighted_select_optsize(i32 %a, i32 %b) #1 {
+    %cmp = icmp ne i32 %a, 0
+    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
+    ret i32 %sel
+
+  ; This function has used the optsize flag, so it will do nothing.
+  ; CHECK-LABEL: weighted_select_optsize
+  ; CHECK:         %cmp = icmp ne i32 %a, 0
+  ; CHECK-NEXT:    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
+  ; CHECK-NEXT:    ret i32 %sel
+  }
+
+  define i32 @weighted_select_pgso(i32 %a, i32 %b) #0 !prof !18 {
+    %cmp = icmp ne i32 %a, 0
+    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
+    ret i32 %sel
+
+  ; The function_entry_count of this function is 0, so it will do nothing.
+  ; CHECK-LABEL: weighted_select_pgso
+  ; CHECK:         %cmp = icmp ne i32 %a, 0
+  ; CHECK-NEXT:    %sel = select i1 %cmp, i32 %a, i32 %b, !prof !15
+  ; CHECK-NEXT:    ret i32 %sel
+  }
+  
+  attributes #0 = { "target-cpu"="pwr9" }
+  attributes #1 = { optsize "target-cpu"="pwr9" }
+  
+  !llvm.module.flags = !{!0}
+  
+  !0 = !{i32 1, !"ProfileSummary", !1}
+  !1 = !{!2, !3, !4, !5, !6, !7, !8, !9}
+  !2 = !{!"ProfileFormat", !"InstrProf"}
+  !3 = !{!"TotalCount", i64 10000}
+  !4 = !{!"MaxCount", i64 10}
+  !5 = !{!"MaxInternalCount", i64 1}
+  !6 = !{!"MaxFunctionCount", i64 1000}
+  !7 = !{!"NumCounts", i64 3}
+  !8 = !{!"NumFunctions", i64 3}
+  !9 = !{!"DetailedSummary", !10}
+  !10 = !{!11, !12, !13}
+  !11 = !{i32 10000, i64 100, i32 1}
+  !12 = !{i32 999000, i64 100, i32 1}
+  !13 = !{i32 999999, i64 1, i32 2}
+  !14 = !{!"branch_weights", i32 1, i32 99}
+  !15 = !{!"branch_weights", i32 1, i32 100}
+  !16 = !{!"branch_weights", i32 100, i32 1}
+  !17 = !{!"branch_weights", i32 0, i32 0}
+  !18 = !{!"function_entry_count", i64 0}
+
+...