Index: include/llvm/Transforms/Utils/CodeExtractor.h
===================================================================
--- include/llvm/Transforms/Utils/CodeExtractor.h
+++ include/llvm/Transforms/Utils/CodeExtractor.h
@@ -64,6 +64,11 @@
     unsigned NumExitBlocks = std::numeric_limits<unsigned>::max();
     Type *RetTy;
 
+    // Suffix to use when creating extracted function (appended to the original
+    // function name). If empty, the default is to append "_" + entry block
+    // label to the original function name.
+    StringRef Suffix;
+
   public:
     /// Create a code extractor for a sequence of blocks.
     ///
@@ -78,7 +83,8 @@
     CodeExtractor(ArrayRef<BasicBlock *> BBs, DominatorTree *DT = nullptr,
                   bool AggregateArgs = false, BlockFrequencyInfo *BFI = nullptr,
                   BranchProbabilityInfo *BPI = nullptr,
-                  bool AllowVarArgs = false, bool AllowAlloca = false);
+                  bool AllowVarArgs = false, bool AllowAlloca = false,
+                  StringRef Suffix = "");
 
     /// Create a code extractor for a loop body.
     ///
@@ -86,7 +92,7 @@
     /// block sequence of the loop.
     CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs = false,
                   BlockFrequencyInfo *BFI = nullptr,
-                  BranchProbabilityInfo *BPI = nullptr);
+                  BranchProbabilityInfo *BPI = nullptr, StringRef Suffix = "");
 
     /// Perform the extraction, returning the new function.
     ///
Index: lib/Transforms/IPO/HotColdSplitting.cpp
===================================================================
--- lib/Transforms/IPO/HotColdSplitting.cpp
+++ lib/Transforms/IPO/HotColdSplitting.cpp
@@ -340,7 +340,9 @@
           llvm::dbgs() << "\nExtracting: " << *BB;);
 
   // TODO: Pass BFI and BPI to update profile information.
-  CodeExtractor CE(Region, DT);
+  CodeExtractor CE(Region, DT, /* AggregateArgs */ false, /* BFI */ nullptr,
+                   /* BPI */ nullptr, /* AllowVarArgs */ false,
+                   /* AllowAlloca */ false, /* Suffix */ ".cold");
 
   SetVector<Value *> Inputs, Outputs, Sinks;
   CE.findInputsOutputs(Inputs, Outputs, Sinks);
Index: lib/Transforms/Utils/CodeExtractor.cpp
===================================================================
--- lib/Transforms/Utils/CodeExtractor.cpp
+++ lib/Transforms/Utils/CodeExtractor.cpp
@@ -228,19 +228,21 @@
 CodeExtractor::CodeExtractor(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
                              bool AggregateArgs, BlockFrequencyInfo *BFI,
                              BranchProbabilityInfo *BPI, bool AllowVarArgs,
-                             bool AllowAlloca)
+                             bool AllowAlloca, StringRef Suffix)
     : DT(DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
       BPI(BPI), AllowVarArgs(AllowVarArgs),
-      Blocks(buildExtractionBlockSet(BBs, DT, AllowVarArgs, AllowAlloca)) {}
+      Blocks(buildExtractionBlockSet(BBs, DT, AllowVarArgs, AllowAlloca)),
+      Suffix(Suffix) {}
 
 CodeExtractor::CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs,
                              BlockFrequencyInfo *BFI,
-                             BranchProbabilityInfo *BPI)
+                             BranchProbabilityInfo *BPI, StringRef Suffix)
     : DT(&DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
       BPI(BPI), AllowVarArgs(false),
       Blocks(buildExtractionBlockSet(L.getBlocks(), &DT,
                                      /* AllowVarArgs */ false,
-                                     /* AllowAlloca */ false)) {}
+                                     /* AllowAlloca */ false)),
+      Suffix(Suffix) {}
 
 /// definedInRegion - Return true if the specified value is defined in the
 /// extracted region.
@@ -672,7 +674,9 @@
   // Create the new function
   Function *newFunction = Function::Create(
       funcType, GlobalValue::InternalLinkage, oldFunction->getAddressSpace(),
-      oldFunction->getName() + "_" + header->getName(), M);
+      Suffix.empty() ? oldFunction->getName() + "_" + header->getName()
+                     : oldFunction->getName() + Suffix,
+      M);
   // If the old function is no-throw, so is the new one.
   if (oldFunction->doesNotThrow())
     newFunction->setDoesNotThrow();
Index: test/Transforms/HotColdSplit/split-cold-2.ll
===================================================================
--- test/Transforms/HotColdSplit/split-cold-2.ll
+++ test/Transforms/HotColdSplit/split-cold-2.ll
@@ -4,10 +4,10 @@
 ; Make sure this compiles. This test used to fail with an invalid phi node: the
 ; two predecessors were outlined and the SSA representation was invalid.
 
-; CHECK: remark: <unknown>:0:0: fun split cold code into fun_if.else
+; CHECK: remark: <unknown>:0:0: fun split cold code into fun.cold
 ; CHECK-LABEL: @fun
 ; CHECK: codeRepl:
-; CHECK-NEXT: call void @fun_if.else
+; CHECK-NEXT: call void @fun.cold
 
 define void @fun() {
 entry:
Index: test/Transforms/HotColdSplit/split-out-dbg-val-of-arg.ll
===================================================================
--- test/Transforms/HotColdSplit/split-out-dbg-val-of-arg.ll
+++ test/Transforms/HotColdSplit/split-out-dbg-val-of-arg.ll
@@ -1,6 +1,6 @@
 ; RUN: opt -hotcoldsplit -S < %s | FileCheck %s
 
-; CHECK-LABEL: define {{.*}}@foo_if.end
+; CHECK-LABEL: define {{.*}}@foo.cold
 ; CHECK-NOT: llvm.dbg.value
 
 define void @foo(i32 %arg1) !dbg !6 {