Index: llvm/include/llvm/Analysis/FunctionAnnotation.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Analysis/FunctionAnnotation.h
@@ -0,0 +1,32 @@
+//= FunctionAnnotation.h - Function Annotation with Function Attributes- C++ =//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the FunctionAnnotation class used to annotate functions
+// with function attributes.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_FUNCTIONANNOTATION_H_
+#define LLVM_ANALYSIS_FUNCTIONANNOTATION_H_
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class FunctionAnnotation : public AnalysisInfoMixin<FunctionAnnotation> {
+  friend AnalysisInfoMixin<FunctionAnnotation>;
+  static AnalysisKey Key;
+
+public:
+  using Result = StringRef;
+  Result run(Function &F, FunctionAnalysisManager &FAM);
+};
+
+} // namespace llvm
+
+#endif // LLVM_ANALYSIS_FUNCTIONANNOTATION_H_
Index: llvm/lib/Analysis/CMakeLists.txt
===================================================================
--- llvm/lib/Analysis/CMakeLists.txt
+++ llvm/lib/Analysis/CMakeLists.txt
@@ -69,6 +69,7 @@
   DomTreeUpdater.cpp
   DominanceFrontier.cpp
   EHPersonalities.cpp
+  FunctionAnnotation.cpp
   FunctionPropertiesAnalysis.cpp
   GlobalsModRef.cpp
   GuardUtils.cpp
Index: llvm/lib/Analysis/FunctionAnnotation.cpp
===================================================================
--- /dev/null
+++ llvm/lib/Analysis/FunctionAnnotation.cpp
@@ -0,0 +1,71 @@
+//=== FunctionAnnotation.cpp - Function Annotation with Function Attributes ==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the FunctionAnnotation class used to annotate functions
+// with function attributes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/FunctionAnnotation.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <fstream>
+#include <sstream>
+
+namespace llvm {
+
+static cl::opt<std::string> FunctionAnnotationAttributeName(
+    "func-annotate-attribute-name", cl::init(""), cl::Hidden,
+    cl::desc("Specify the name of the attribute to annotate functions with."));
+
+static cl::opt<std::string> FunctionAnnotationCSVPath(
+    "func-annotate-csv-path", cl::init("-"), cl::Hidden,
+    cl::desc("Specify the path to the CSV file containing the functions and "
+             "their attribute values.\nCSV file header should have the format: "
+             "[Index, Function Name, Attribute Value]"));
+
+AnalysisKey FunctionAnnotation::Key;
+
+FunctionAnnotation::Result
+FunctionAnnotation::run(Function &F, FunctionAnalysisManager &AM) {
+  const StringRef FunctionName = F.getName();
+
+  if (FunctionAnnotationAttributeName.empty()) {
+    report_fatal_error(
+        "Name of the function annotation attribute not specified.");
+  }
+  const Attribute &A = F.getFnAttribute(FunctionAnnotationAttributeName);
+  const StringRef FnOptLevel = A.getValueAsString();
+
+  if (FnOptLevel.empty()) {
+    std::ifstream InputFile;
+    InputFile.open(FunctionAnnotationCSVPath);
+    if (!InputFile.is_open()) {
+      report_fatal_error("Function annotation CSV file not found.");
+    }
+
+    std::string Line;
+    while (std::getline(InputFile, Line)) {
+      std::istringstream ISS(Line);
+      std::string ID, Name, OLevel;
+
+      if (std::getline(ISS, ID, ',') && std::getline(ISS, Name, ',') &&
+          std::getline(ISS, OLevel)) {
+        char *endp = nullptr;
+        if (Name.c_str() != endp && Name == FunctionName) {
+          F.addFnAttr(FunctionAnnotationAttributeName, OLevel);
+          break;
+        }
+      }
+    }
+    InputFile.close();
+  }
+  return FnOptLevel;
+}
+
+} // namespace llvm
Index: llvm/lib/Passes/PassBuilder.cpp
===================================================================
--- llvm/lib/Passes/PassBuilder.cpp
+++ llvm/lib/Passes/PassBuilder.cpp
@@ -34,6 +34,7 @@
 #include "llvm/Analysis/DependenceAnalysis.h"
 #include "llvm/Analysis/DivergenceAnalysis.h"
 #include "llvm/Analysis/DominanceFrontier.h"
+#include "llvm/Analysis/FunctionAnnotation.h"
 #include "llvm/Analysis/FunctionPropertiesAnalysis.h"
 #include "llvm/Analysis/GlobalsModRef.h"
 #include "llvm/Analysis/IRSimilarityIdentifier.h"
Index: llvm/lib/Passes/PassRegistry.def
===================================================================
--- llvm/lib/Passes/PassRegistry.def
+++ llvm/lib/Passes/PassRegistry.def
@@ -155,6 +155,7 @@
 FUNCTION_ANALYSIS("postdomtree", PostDominatorTreeAnalysis())
 FUNCTION_ANALYSIS("demanded-bits", DemandedBitsAnalysis())
 FUNCTION_ANALYSIS("domfrontier", DominanceFrontierAnalysis())
+FUNCTION_ANALYSIS("func-annotate", FunctionAnnotation())
 FUNCTION_ANALYSIS("func-properties", FunctionPropertiesAnalysis())
 FUNCTION_ANALYSIS("loops", LoopAnalysis())
 FUNCTION_ANALYSIS("lazy-value-info", LazyValueAnalysis())
Index: llvm/test/Analysis/FunctionAnnotation/Inputs/matmul-look-up-table.csv
===================================================================
--- /dev/null
+++ llvm/test/Analysis/FunctionAnnotation/Inputs/matmul-look-up-table.csv
@@ -0,0 +1,3 @@
+Index,Function,OptimizationLevel
+0,multiply,O2
+1,main,O1
Index: llvm/test/Analysis/FunctionAnnotation/matmul.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/FunctionAnnotation/matmul.ll
@@ -0,0 +1,125 @@
+; RUN: opt < %s -passes="require<func-annotate>" -func-annotate-attribute-name=opt-level -func-annotate-csv-path=%S/Inputs/matmul-look-up-table.csv -S | FileCheck %s
+
+define i32 @main() {
+; CHECK: define i32 @main() #0
+entry:
+  %retval = alloca i32, align 4
+  %mat1 = alloca [2 x [2 x i32]], align 16
+  %mat2 = alloca [2 x [2 x i32]], align 16
+  %res = alloca [2 x [2 x i32]], align 16
+  %i = alloca i32, align 4
+  %j = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  %arraydecay = getelementptr inbounds [2 x [2 x i32]], [2 x [2 x i32]]* %mat1, i64 0, i64 0
+  %arraydecay1 = getelementptr inbounds [2 x [2 x i32]], [2 x [2 x i32]]* %mat2, i64 0, i64 0
+  %arraydecay2 = getelementptr inbounds [2 x [2 x i32]], [2 x [2 x i32]]* %res, i64 0, i64 0
+  call void @multiply([2 x i32]* %arraydecay, [2 x i32]* %arraydecay1, [2 x i32]* %arraydecay2)
+  ret i32 0
+}
+
+define void @multiply([2 x i32]* %mat1, [2 x i32]* %mat2, [2 x i32]* %res) {
+; CHECK: define void @multiply([2 x i32]* %mat1, [2 x i32]* %mat2, [2 x i32]* %res) #1
+entry:
+  %mat1.addr = alloca [2 x i32]*, align 8
+  %mat2.addr = alloca [2 x i32]*, align 8
+  %res.addr = alloca [2 x i32]*, align 8
+  %i = alloca i32, align 4
+  %j = alloca i32, align 4
+  %k = alloca i32, align 4
+  store [2 x i32]* %mat1, [2 x i32]** %mat1.addr, align 8
+  store [2 x i32]* %mat2, [2 x i32]** %mat2.addr, align 8
+  store [2 x i32]* %res, [2 x i32]** %res.addr, align 8
+  store i32 0, i32* %i, align 4
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc24, %entry
+  %0 = load i32, i32* %i, align 4
+  %cmp = icmp slt i32 %0, 2
+  br i1 %cmp, label %for.body, label %for.end26
+
+for.body:                                         ; preds = %for.cond
+  store i32 0, i32* %j, align 4
+  br label %for.cond1
+
+for.cond1:                                        ; preds = %for.inc21, %for.body
+  %1 = load i32, i32* %j, align 4
+  %cmp2 = icmp slt i32 %1, 2
+  br i1 %cmp2, label %for.body3, label %for.end23
+
+for.body3:                                        ; preds = %for.cond1
+  %2 = load [2 x i32]*, [2 x i32]** %res.addr, align 8
+  %3 = load i32, i32* %i, align 4
+  %idxprom = sext i32 %3 to i64
+  %arrayidx = getelementptr inbounds [2 x i32], [2 x i32]* %2, i64 %idxprom
+  %4 = load i32, i32* %j, align 4
+  %idxprom4 = sext i32 %4 to i64
+  %arrayidx5 = getelementptr inbounds [2 x i32], [2 x i32]* %arrayidx, i64 0, i64 %idxprom4
+  store i32 0, i32* %arrayidx5, align 4
+  store i32 0, i32* %k, align 4
+  br label %for.cond6
+
+for.cond6:                                        ; preds = %for.inc, %for.body3
+  %5 = load i32, i32* %k, align 4
+  %cmp7 = icmp slt i32 %5, 2
+  br i1 %cmp7, label %for.body8, label %for.end
+
+for.body8:                                        ; preds = %for.cond6
+  %6 = load [2 x i32]*, [2 x i32]** %mat1.addr, align 8
+  %7 = load i32, i32* %i, align 4
+  %idxprom9 = sext i32 %7 to i64
+  %arrayidx10 = getelementptr inbounds [2 x i32], [2 x i32]* %6, i64 %idxprom9
+  %8 = load i32, i32* %k, align 4
+  %idxprom11 = sext i32 %8 to i64
+  %arrayidx12 = getelementptr inbounds [2 x i32], [2 x i32]* %arrayidx10, i64 0, i64 %idxprom11
+  %9 = load i32, i32* %arrayidx12, align 4
+  %10 = load [2 x i32]*, [2 x i32]** %mat2.addr, align 8
+  %11 = load i32, i32* %k, align 4
+  %idxprom13 = sext i32 %11 to i64
+  %arrayidx14 = getelementptr inbounds [2 x i32], [2 x i32]* %10, i64 %idxprom13
+  %12 = load i32, i32* %j, align 4
+  %idxprom15 = sext i32 %12 to i64
+  %arrayidx16 = getelementptr inbounds [2 x i32], [2 x i32]* %arrayidx14, i64 0, i64 %idxprom15
+  %13 = load i32, i32* %arrayidx16, align 4
+  %mul = mul nsw i32 %9, %13
+  %14 = load [2 x i32]*, [2 x i32]** %res.addr, align 8
+  %15 = load i32, i32* %i, align 4
+  %idxprom17 = sext i32 %15 to i64
+  %arrayidx18 = getelementptr inbounds [2 x i32], [2 x i32]* %14, i64 %idxprom17
+  %16 = load i32, i32* %j, align 4
+  %idxprom19 = sext i32 %16 to i64
+  %arrayidx20 = getelementptr inbounds [2 x i32], [2 x i32]* %arrayidx18, i64 0, i64 %idxprom19
+  %17 = load i32, i32* %arrayidx20, align 4
+  %add = add nsw i32 %17, %mul
+  store i32 %add, i32* %arrayidx20, align 4
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body8
+  %18 = load i32, i32* %k, align 4
+  %inc = add nsw i32 %18, 1
+  store i32 %inc, i32* %k, align 4
+  br label %for.cond6
+
+for.end:                                          ; preds = %for.cond6
+  br label %for.inc21
+
+for.inc21:                                        ; preds = %for.end
+  %19 = load i32, i32* %j, align 4
+  %inc22 = add nsw i32 %19, 1
+  store i32 %inc22, i32* %j, align 4
+  br label %for.cond1
+
+for.end23:                                        ; preds = %for.cond1
+  br label %for.inc24
+
+for.inc24:                                        ; preds = %for.end23
+  %20 = load i32, i32* %i, align 4
+  %inc25 = add nsw i32 %20, 1
+  store i32 %inc25, i32* %i, align 4
+  br label %for.cond
+
+for.end26:                                        ; preds = %for.cond
+  ret void
+}
+
+; CHECK: attributes #0 = { "opt-level"="O1" }
+; CHECK: attributes #1 = { "opt-level"="O2" }