diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -74,6 +74,7 @@
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/Utils/CallPromotionUtils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/MisExpect.h"
 #include "llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h"
 #include "llvm/Transforms/Utils/SampleProfileLoaderBaseUtil.h"
 #include <algorithm>
@@ -1704,10 +1705,7 @@
       }
     }
 
-    // FIXME: Re-enable for sample profiling after investigating why the sum
-    // of branch weights can be 0
-    //
-    // misexpect::checkExpectAnnotations(*TI, Weights, /*IsFrontend=*/false);
+    misexpect::checkExpectAnnotations(*TI, Weights, /*IsFrontend=*/false);
 
     uint64_t TempWeight;
     // Only set weights if there is at least one non-zero weight.
diff --git a/llvm/lib/Transforms/Utils/MisExpect.cpp b/llvm/lib/Transforms/Utils/MisExpect.cpp
--- a/llvm/lib/Transforms/Utils/MisExpect.cpp
+++ b/llvm/lib/Transforms/Utils/MisExpect.cpp
@@ -163,6 +163,8 @@
   // We cannot calculate branch probability if either of these invariants aren't
   // met. However, MisExpect diagnostics should not prevent code from compiling,
   // so we simply forgo emitting diagnostics here, and return early.
+  // assert((TotalBranchWeight >= LikelyBranchWeight) && (TotalBranchWeight > 0)
+  //              && "TotalBranchWeight is less than the Likely branch weight");
   if ((TotalBranchWeight == 0) || (TotalBranchWeight <= LikelyBranchWeight))
     return;
 
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/misexpect.prof b/llvm/test/Transforms/SampleProfile/Inputs/misexpect.prof
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/misexpect.prof
@@ -0,0 +1,10 @@
+main:15680:2500
+ 1: 2500
+ 4: 1000
+ 5: 1000
+ 6: 800
+ 7: 500
+ 9: 10226
+ 10: 2243
+ 16: 0
+ 18: 0
diff --git a/llvm/test/Transforms/SampleProfile/misexpect-zero.ll b/llvm/test/Transforms/SampleProfile/misexpect-zero.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/misexpect-zero.ll
@@ -0,0 +1,85 @@
+; Ensure MisExpect does not crash when given branches with zero weights
+
+; RUN: opt < %s -passes="sample-profile" -sample-profile-file=%S/Inputs/misexpect.prof -pgo-warn-misexpect -S 2>&1  | FileCheck %s
+
+define i32 @main() #0 !dbg !36 {
+ ; CHECK-LABEL: @main(
+; CHECK-NEXT: for.cond:
+; CHECK-NEXT: %0 = load i32, i32* null, align 4, !dbg !44
+; CHECK-NEXT: br i1 false, label %for.body, label %for.end, !prof !49
+; CHECK: for.body:
+; CHECK-NEXT: ret i32 0
+; CHECK: for.end:
+; CHECK-NEXT: ret i32 0
+; NOT: warning:
+for.cond:
+  %0 = load i32, i32* null, align 4, !dbg !43
+  br i1 false, label %for.body, label %for.end, !prof !48
+
+for.body:                                         ; preds = %for.cond
+  ret i32 0
+
+for.end:                                          ; preds = %for.cond
+  ret i32 0
+}
+
+; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { "use-sample-profile" }
+attributes #1 = { nocallback nofree nosync nounwind readnone speculatable willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!5, !6, !7}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 248211) (llvm/trunk 248217)", isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug, enums: !2, retainedTypes: !3)
+!1 = !DIFile(filename: "test.cc", directory: "/ssd/llvm_commit")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIBasicType(name: "double", size: 64, align: 64, encoding: DW_ATE_float)
+!5 = !{i32 2, !"Dwarf Version", i32 4}
+!6 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = !{i32 1, !"ProfileSummary", !8}
+!8 = !{!9, !10, !11, !12, !13, !14, !15, !16, !17, !18}
+!9 = !{!"ProfileFormat", !"SampleProfile"}
+!10 = !{!"TotalCount", i64 0}
+!11 = !{!"MaxCount", i64 0}
+!12 = !{!"MaxInternalCount", i64 0}
+!13 = !{!"MaxFunctionCount", i64 0}
+!14 = !{!"NumCounts", i64 9}
+!15 = !{!"NumFunctions", i64 1}
+!16 = !{!"IsPartialProfile", i64 0}
+!17 = !{!"PartialProfileRatio", double 0.000000e+00}
+!18 = !{!"DetailedSummary", !19}
+!19 = !{!20, !21, !22, !23, !24, !25, !26, !27, !28, !29, !30, !31, !32, !33, !34, !35}
+!20 = !{i32 10000, i64 0, i32 0}
+!21 = !{i32 100000, i64 0, i32 0}
+!22 = !{i32 200000, i64 0, i32 0}
+!23 = !{i32 300000, i64 0, i32 0}
+!24 = !{i32 400000, i64 0, i32 0}
+!25 = !{i32 500000, i64 0, i32 0}
+!26 = !{i32 600000, i64 0, i32 0}
+!27 = !{i32 700000, i64 0, i32 0}
+!28 = !{i32 800000, i64 0, i32 0}
+!29 = !{i32 900000, i64 0, i32 0}
+!30 = !{i32 950000, i64 0, i32 0}
+!31 = !{i32 990000, i64 0, i32 0}
+!32 = !{i32 999000, i64 0, i32 0}
+!33 = !{i32 999900, i64 0, i32 0}
+!34 = !{i32 999990, i64 0, i32 0}
+!35 = !{i32 999999, i64 0, i32 0}
+!36 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 4, type: !37, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!37 = !DISubroutineType(types: !38)
+!38 = !{!39, !39, !40}
+!39 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!40 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !41, size: 64, align: 64)
+!41 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !42, size: 64, align: 64)
+!42 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_signed_char)
+!43 = !DILocation(line: 11, column: 22, scope: !44)
+!44 = distinct !DILexicalBlock(scope: !45, file: !1, line: 11, column: 6)
+!45 = distinct !DILexicalBlock(scope: !46, file: !1, line: 11, column: 6)
+!46 = distinct !DILexicalBlock(scope: !47, file: !1, line: 9, column: 21)
+!47 = distinct !DILexicalBlock(scope: !36, file: !1, line: 9, column: 8)
+; These branch weights shouldn't be removed by these passes
+; CHECK: !{{[0-9]+}} = !{!"branch_weights", i32 0, i32 0}
+!48 = !{!"branch_weights", i32 0, i32 0}
diff --git a/llvm/test/Transforms/SampleProfile/misexpect.ll b/llvm/test/Transforms/SampleProfile/misexpect.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/misexpect.ll
@@ -0,0 +1,250 @@
+; Test that misexpect diagnostics are issued in sample profiling
+; RUN: opt < %s -passes="function(lower-expect),sample-profile" -sample-profile-file=%S/Inputs/misexpect.prof -pgo-warn-misexpect -S 2>&1  | FileCheck %s --check-prefix=WARNING
+
+; Test that if expect intrinsics are not lowered, then no diagnostics are issued
+; RUN: opt < %s -passes="sample-profile" -sample-profile-file=%S/Inputs/misexpect.prof -pgo-warn-misexpect -S 2>&1  | FileCheck %s --check-prefix=NONE
+
+; Original C++ code for this test case:
+;
+; #include <stdio.h>
+; #include <stdlib.h>
+
+; int main(int argc, char *argv[]) {
+;   if (argc < 2)
+;     return 1;
+;   double result;
+;   int limit = atoi(argv[1]);
+;   if (limit > 100) {
+;     double s = 23.041968 * atoi(argv[2]);
+;     for (int u = 0; u < limit; u++) {
+;       double x = s;
+;       s = x + 3.049 + (double)u;
+;       s -= s + 3.94 / x * 0.32;
+;     }
+;     result = s;
+;   } else {
+;     result = atoi(argv[2]);
+;   }
+;   printf("result is %lf\n", result);
+;   return 0;
+; }
+
+; WARNING-DAG: warning: test.cc:9:14: 20.06%
+; WARNING-DAG: warning: test.cc:11:24: 92.74%
+
+; NONE-NOT: warning: test.cc:9:14: 20.06%
+; NONE-NOT: warning: test.cc:11:24: 92.74%
+
+@.str = private unnamed_addr constant [15 x i8] c"result is %lf\0A\00", align 1
+
+; Function Attrs: uwtable
+define i32 @main(i32 %argc, i8** %argv) #0 !dbg !6 {
+
+entry:
+  %retval = alloca i32, align 4
+  %argc.addr = alloca i32, align 4
+  %argv.addr = alloca i8**, align 8
+  %result = alloca double, align 8
+  %limit = alloca i32, align 4
+  %s = alloca double, align 8
+  %u = alloca i32, align 4
+  %x = alloca double, align 8
+  store i32 0, i32* %retval, align 4
+  store i32 %argc, i32* %argc.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %argc.addr, metadata !16, metadata !17), !dbg !18
+  store i8** %argv, i8*** %argv.addr, align 8
+  call void @llvm.dbg.declare(metadata i8*** %argv.addr, metadata !19, metadata !17), !dbg !20
+  %0 = load i32, i32* %argc.addr, align 4, !dbg !21
+  %cmp = icmp slt i32 %0, 2, !dbg !23
+  br i1 %cmp, label %if.then, label %if.end, !dbg !24
+
+if.then:                                          ; preds = %entry
+  store i32 1, i32* %retval, align 4, !dbg !25
+  br label %return, !dbg !25
+
+if.end:                                           ; preds = %entry
+  call void @llvm.dbg.declare(metadata double* %result, metadata !26, metadata !17), !dbg !27
+  call void @llvm.dbg.declare(metadata i32* %limit, metadata !28, metadata !17), !dbg !29
+  %1 = load i8**, i8*** %argv.addr, align 8, !dbg !30
+  %arrayidx = getelementptr inbounds i8*, i8** %1, i64 1, !dbg !30
+  %2 = load i8*, i8** %arrayidx, align 8, !dbg !30
+  %call = call i32 @atoi(i8* %2) #4, !dbg !31
+  store i32 %call, i32* %limit, align 4, !dbg !29
+  %3 = load i32, i32* %limit, align 4, !dbg !32
+  %exp = call i32 @llvm.expect.i32(i32 %3, i32 0)
+  %tobool = icmp ne i32 %exp, 0, !dbg !34
+  br i1 %tobool, label %if.then.2, label %if.else, !dbg !35
+
+if.then.2:                                        ; preds = %if.end
+  call void @llvm.dbg.declare(metadata double* %s, metadata !36, metadata !17), !dbg !38
+  %4 = load i8**, i8*** %argv.addr, align 8, !dbg !39
+  %arrayidx3 = getelementptr inbounds i8*, i8** %4, i64 2, !dbg !39
+  %5 = load i8*, i8** %arrayidx3, align 8, !dbg !39
+  %call4 = call i32 @atoi(i8* %5) #4, !dbg !40
+  %conv = sitofp i32 %call4 to double, !dbg !40
+  %mul = fmul double 0x40370ABE6A337A81, %conv, !dbg !41
+  store double %mul, double* %s, align 8, !dbg !38
+  call void @llvm.dbg.declare(metadata i32* %u, metadata !42, metadata !17), !dbg !44
+  store i32 0, i32* %u, align 4, !dbg !44
+  br label %for.cond, !dbg !45
+
+for.cond:                                         ; preds = %for.inc, %if.then.2
+  %6 = load i32, i32* %u, align 4, !dbg !46
+  %7 = load i32, i32* %limit, align 4, !dbg !48
+  %expval = call i32 @llvm.expect.i32(i32 %6, i32 1)
+  %cmp5 = icmp ne i32 %expval, 0, !dbg !49
+  br i1 %cmp5, label %for.body, label %for.end, !dbg !50
+
+for.body:                                         ; preds = %for.cond
+  call void @llvm.dbg.declare(metadata double* %x, metadata !51, metadata !17), !dbg !53
+  %8 = load double, double* %s, align 8, !dbg !54
+  store double %8, double* %x, align 8, !dbg !53
+  %9 = load double, double* %x, align 8, !dbg !55
+  %add = fadd double %9, 3.049000e+00, !dbg !56
+  %10 = load i32, i32* %u, align 4, !dbg !57
+  %conv6 = sitofp i32 %10 to double, !dbg !57
+  %add7 = fadd double %add, %conv6, !dbg !58
+  store double %add7, double* %s, align 8, !dbg !59
+  %11 = load double, double* %s, align 8, !dbg !60
+  %12 = load double, double* %x, align 8, !dbg !61
+  %div = fdiv double 3.940000e+00, %12, !dbg !62
+  %mul8 = fmul double %div, 3.200000e-01, !dbg !63
+  %add9 = fadd double %11, %mul8, !dbg !64
+  %13 = load double, double* %s, align 8, !dbg !65
+  %sub = fsub double %13, %add9, !dbg !65
+  store double %sub, double* %s, align 8, !dbg !65
+  br label %for.inc, !dbg !66
+
+for.inc:                                          ; preds = %for.body
+  %14 = load i32, i32* %u, align 4, !dbg !67
+  %inc = add nsw i32 %14, 1, !dbg !67
+  store i32 %inc, i32* %u, align 4, !dbg !67
+  br label %for.cond, !dbg !68
+
+for.end:                                          ; preds = %for.cond
+  %15 = load double, double* %s, align 8, !dbg !69
+  store double %15, double* %result, align 8, !dbg !70
+  br label %if.end.13, !dbg !71
+
+if.else:                                          ; preds = %if.end
+  %16 = load i8**, i8*** %argv.addr, align 8, !dbg !72
+  %arrayidx10 = getelementptr inbounds i8*, i8** %16, i64 2, !dbg !72
+  %17 = load i8*, i8** %arrayidx10, align 8, !dbg !72
+  %call11 = call i32 @atoi(i8* %17) #4, !dbg !74
+  %conv12 = sitofp i32 %call11 to double, !dbg !74
+  store double %conv12, double* %result, align 8, !dbg !75
+  br label %if.end.13
+
+if.end.13:                                        ; preds = %if.else, %for.end
+  %18 = load double, double* %result, align 8, !dbg !76
+  %call14 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str, i32 0, i32 0), double %18), !dbg !77
+  store i32 0, i32* %retval, align 4, !dbg !78
+  br label %return, !dbg !78
+
+return:                                           ; preds = %if.end.13, %if.then
+  %19 = load i32, i32* %retval, align 4, !dbg !79
+  ret i32 %19, !dbg !79
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind readonly
+declare i32 @atoi(i8*) #2
+
+declare i32 @printf(i8*, ...) #3
+
+; Function Attrs: nounwind readnone willreturn
+declare i32 @llvm.expect.i32(i32, i32) #5
+
+
+attributes #0 = { uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" "use-sample-profile" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { nounwind readonly "disable-tail-calls"="false" "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #3 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #4 = { nounwind readonly }
+attributes #5 = { nounwind readnone willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!13, !14}
+!llvm.ident = !{!15}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 248211) (llvm/trunk 248217)", isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug, enums: !2, retainedTypes: !3)
+!1 = !DIFile(filename: "test.cc", directory: "/ssd/llvm_commit")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIBasicType(name: "double", size: 64, align: 64, encoding: DW_ATE_float)
+!6 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 4, type: !7, isLocal: false, isDefinition: true, scopeLine: 4, flags: DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !9, !10}
+!9 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64, align: 64)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64, align: 64)
+!12 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_signed_char)
+!13 = !{i32 2, !"Dwarf Version", i32 4}
+!14 = !{i32 2, !"Debug Info Version", i32 3}
+!15 = !{!"clang version 3.8.0 (trunk 248211) (llvm/trunk 248217)"}
+!16 = !DILocalVariable(name: "argc", arg: 1, scope: !6, file: !1, line: 4, type: !9)
+!17 = !DIExpression()
+!18 = !DILocation(line: 4, column: 15, scope: !6)
+!19 = !DILocalVariable(name: "argv", arg: 2, scope: !6, file: !1, line: 4, type: !10)
+!20 = !DILocation(line: 4, column: 27, scope: !6)
+!21 = !DILocation(line: 5, column: 8, scope: !22)
+!22 = distinct !DILexicalBlock(scope: !6, file: !1, line: 5, column: 8)
+!23 = !DILocation(line: 5, column: 13, scope: !22)
+!24 = !DILocation(line: 5, column: 8, scope: !6)
+!25 = !DILocation(line: 6, column: 6, scope: !22)
+!26 = !DILocalVariable(name: "result", scope: !6, file: !1, line: 7, type: !4)
+!27 = !DILocation(line: 7, column: 11, scope: !6)
+!28 = !DILocalVariable(name: "limit", scope: !6, file: !1, line: 8, type: !9)
+!29 = !DILocation(line: 8, column: 8, scope: !6)
+!30 = !DILocation(line: 8, column: 21, scope: !6)
+!31 = !DILocation(line: 8, column: 16, scope: !6)
+!32 = !DILocation(line: 9, column: 8, scope: !33)
+!33 = distinct !DILexicalBlock(scope: !6, file: !1, line: 9, column: 8)
+!34 = !DILocation(line: 9, column: 14, scope: !33)
+!35 = !DILocation(line: 9, column: 8, scope: !6)
+!36 = !DILocalVariable(name: "s", scope: !37, file: !1, line: 10, type: !4)
+!37 = distinct !DILexicalBlock(scope: !33, file: !1, line: 9, column: 21)
+!38 = !DILocation(line: 10, column: 13, scope: !37)
+!39 = !DILocation(line: 10, column: 34, scope: !37)
+!40 = !DILocation(line: 10, column: 29, scope: !37)
+!41 = !DILocation(line: 10, column: 27, scope: !37)
+!42 = !DILocalVariable(name: "u", scope: !43, file: !1, line: 11, type: !9)
+!43 = distinct !DILexicalBlock(scope: !37, file: !1, line: 11, column: 6)
+!44 = !DILocation(line: 11, column: 15, scope: !43)
+!45 = !DILocation(line: 11, column: 11, scope: !43)
+!46 = !DILocation(line: 11, column: 22, scope: !47)
+!47 = distinct !DILexicalBlock(scope: !43, file: !1, line: 11, column: 6)
+!48 = !DILocation(line: 11, column: 26, scope: !47)
+!49 = !DILocation(line: 11, column: 24, scope: !47)
+!50 = !DILocation(line: 11, column: 6, scope: !43)
+!51 = !DILocalVariable(name: "x", scope: !52, file: !1, line: 12, type: !4)
+!52 = distinct !DILexicalBlock(scope: !47, file: !1, line: 11, column: 38)
+!53 = !DILocation(line: 12, column: 15, scope: !52)
+!54 = !DILocation(line: 12, column: 19, scope: !52)
+!55 = !DILocation(line: 13, column: 12, scope: !52)
+!56 = !DILocation(line: 13, column: 14, scope: !52)
+!57 = !DILocation(line: 13, column: 32, scope: !52)
+!58 = !DILocation(line: 13, column: 22, scope: !52)
+!59 = !DILocation(line: 13, column: 10, scope: !52)
+!60 = !DILocation(line: 14, column: 13, scope: !52)
+!61 = !DILocation(line: 14, column: 24, scope: !52)
+!62 = !DILocation(line: 14, column: 22, scope: !52)
+!63 = !DILocation(line: 14, column: 26, scope: !52)
+!64 = !DILocation(line: 14, column: 15, scope: !52)
+!65 = !DILocation(line: 14, column: 10, scope: !52)
+!66 = !DILocation(line: 15, column: 6, scope: !52)
+!67 = !DILocation(line: 11, column: 34, scope: !47)
+!68 = !DILocation(line: 11, column: 6, scope: !47)
+!69 = !DILocation(line: 16, column: 15, scope: !37)
+!70 = !DILocation(line: 16, column: 13, scope: !37)
+!71 = !DILocation(line: 17, column: 4, scope: !37)
+!72 = !DILocation(line: 18, column: 20, scope: !73)
+!73 = distinct !DILexicalBlock(scope: !33, file: !1, line: 17, column: 11)
+!74 = !DILocation(line: 18, column: 15, scope: !73)
+!75 = !DILocation(line: 18, column: 13, scope: !73)
+!76 = !DILocation(line: 20, column: 30, scope: !6)
+!77 = !DILocation(line: 20, column: 4, scope: !6)
+!78 = !DILocation(line: 21, column: 4, scope: !6)
+!79 = !DILocation(line: 22, column: 2, scope: !6)