Index: llvm/lib/Transforms/IPO/HotColdSplitting.cpp
===================================================================
--- llvm/lib/Transforms/IPO/HotColdSplitting.cpp
+++ llvm/lib/Transforms/IPO/HotColdSplitting.cpp
@@ -44,6 +44,7 @@
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PassManager.h"
+#include "llvm/IR/ProfDataUtils.h"
 #include "llvm/IR/User.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/CommandLine.h"
@@ -102,11 +103,35 @@
   return !(isa<ReturnInst>(I) || isa<IndirectBrInst>(I));
 }
 
-bool unlikelyExecuted(BasicBlock &BB) {
+void analyzeProfMetadata(BasicBlock &BB, SmallPtrSetImpl<BasicBlock *> &AnnotatedColdBlocks) {
+  // TODO: Handle branches with > 2 successors.
+  BranchInst *CondBr = dyn_cast<BranchInst>(BB.getTerminator());
+  if (!CondBr)
+    return;
+
+  uint64_t TrueWeight, FalseWeight;
+  if (!extractBranchWeights(*CondBr, TrueWeight, FalseWeight))
+    return;
+
+  if (TrueWeight + FalseWeight == 0)
+    return;
+
+  if (BranchProbability(TrueWeight, TrueWeight + FalseWeight) <= BranchProbability(1, 1000))
+    AnnotatedColdBlocks.insert(CondBr->getSuccessor(0));
+
+  if (BranchProbability(FalseWeight, TrueWeight + FalseWeight) <= BranchProbability(1, 1000))
+    AnnotatedColdBlocks.insert(CondBr->getSuccessor(1));
+}
+
+bool unlikelyExecuted(BasicBlock &BB, SmallPtrSetImpl<BasicBlock *> &AnnotatedColdBlocks) {
   // Exception handling blocks are unlikely executed.
   if (BB.isEHPad() || isa<ResumeInst>(BB.getTerminator()))
     return true;
 
+  analyzeProfMetadata(BB, AnnotatedColdBlocks);
+  if (AnnotatedColdBlocks.count(&BB))
+    return true;
+
   // The block is cold if it calls/invokes a cold function. However, do not
   // mark sanitizer traps as cold.
   for (Instruction &I : BB)
@@ -564,6 +589,7 @@
 
   // The set of cold blocks.
   SmallPtrSet<BasicBlock *, 4> ColdBlocks;
+  SmallPtrSet<BasicBlock *, 4> AnnotatedColdBlocks;
 
   // The worklist of non-intersecting regions left to outline.
   SmallVector<OutliningRegion, 2> OutliningWorklist;
@@ -595,7 +621,7 @@
       continue;
 
     bool Cold = (BFI && PSI->isColdBlock(BB, BFI)) ||
-                (EnableStaticAnalysis && unlikelyExecuted(*BB));
+                (EnableStaticAnalysis && unlikelyExecuted(*BB, AnnotatedColdBlocks));
     if (!Cold)
       continue;
 
Index: llvm/test/Transforms/HotColdSplit/split-static-profile.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/HotColdSplit/split-static-profile.ll
@@ -0,0 +1,84 @@
+; RUN: opt -S -passes=hotcoldsplit < %s | FileCheck %s
+
+; Check that the unlikely branch is outlined.
+; int cold(const char*);
+; int hot(const char*);
+; void foo(int a, int b) {
+;   if (a == b) [[unlikely]] { // Should be outlined.
+;     cold("same");
+;     cold("same");
+;   } else {
+;     hot("different");
+;   }
+; }
+
+; void bar(int a, int b) {
+;   if (a == b) [[likely]] {
+;     hot("same");
+;   } else { // Should be outlined.
+;     cold("different");
+;     cold("different");
+;   }
+; }
+
+
+; CHECK: internal void @foo.cold.1() #[[ATTR0:[0-9]+]]
+; CHECK-NEXT: newFuncRoot
+; CHECK: tail call noundef i32 @cold
+; CHECK: tail call noundef i32 @cold
+
+; CHECK: internal void @bar.cold.1() #[[ATTR0:[0-9]+]]
+; CHECK-NEXT: newFuncRoot
+; CHECK: tail call noundef i32 @cold
+; CHECK: tail call noundef i32 @cold
+; attributes #[[ATTR0]] = { cold minsize }
+
+source_filename = "/app/example.cpp"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@.str = private unnamed_addr constant [5 x i8] c"same\00", align 1
+@.str.1 = private unnamed_addr constant [10 x i8] c"different\00", align 1
+
+define dso_local void @foo(i32 noundef %a, i32 noundef %b) local_unnamed_addr {
+entry:
+  %cmp = icmp eq i32 %a, %b
+  br i1 %cmp, label %if.then, label %if.else, !prof !1
+
+if.then:
+  %call = tail call noundef i32 @cold(ptr noundef nonnull @.str)
+  %call1 = tail call noundef i32 @cold(ptr noundef nonnull @.str)
+  br label %if.end
+
+if.else:
+  %call2 = tail call noundef i32 @hot(ptr noundef nonnull @.str.1)
+  br label %if.end
+
+if.end:
+  ret void
+}
+
+declare noundef i32 @cold(ptr noundef) local_unnamed_addr #1
+
+declare noundef i32 @hot(ptr noundef) local_unnamed_addr #1
+
+define dso_local void @bar(i32 noundef %a, i32 noundef %b) local_unnamed_addr {
+entry:
+  %cmp = icmp eq i32 %a, %b
+  br i1 %cmp, label %if.then, label %if.else, !prof !2
+
+if.then:
+  %call = tail call noundef i32 @hot(ptr noundef nonnull @.str)
+  br label %if.end
+
+if.else:
+  %call1 = tail call noundef i32 @cold(ptr noundef nonnull @.str.1)
+  %call2 = tail call noundef i32 @cold(ptr noundef nonnull @.str.1)
+  br label %if.end
+
+if.end:
+  ret void
+}
+
+!1 = !{!"branch_weights", i32 1, i32 2000}
+!2 = !{!"branch_weights", i32 2000, i32 1}
\ No newline at end of file