diff --git a/llvm/tools/llvm-profgen/PerfReader.h b/llvm/tools/llvm-profgen/PerfReader.h
--- a/llvm/tools/llvm-profgen/PerfReader.h
+++ b/llvm/tools/llvm-profgen/PerfReader.h
@@ -373,6 +373,7 @@
   BranchSample BranchCounter;
 
   void recordRangeCount(uint64_t Start, uint64_t End, uint64_t Repeat) {
+    assert(Start <= End && "invalid instruction range");
     RangeCounter[{Start, End}] += Repeat;
   }
   void recordBranchCount(uint64_t Source, uint64_t Target, uint64_t Repeat) {
diff --git a/llvm/tools/llvm-profgen/PerfReader.cpp b/llvm/tools/llvm-profgen/PerfReader.cpp
--- a/llvm/tools/llvm-profgen/PerfReader.cpp
+++ b/llvm/tools/llvm-profgen/PerfReader.cpp
@@ -422,8 +422,11 @@
     Token.split(Addresses, "/");
     uint64_t Src;
     uint64_t Dst;
-    Addresses[0].substr(2).getAsInteger(16, Src);
-    Addresses[1].substr(2).getAsInteger(16, Dst);
+
+    // Stop at broken LBR records.
+    if (Addresses[0].substr(2).getAsInteger(16, Src) ||
+        Addresses[1].substr(2).getAsInteger(16, Dst))
+      break;
 
     bool SrcIsInternal = Binary->addressIsCode(Src);
     bool DstIsInternal = Binary->addressIsCode(Dst);
diff --git a/llvm/tools/llvm-profgen/ProfileGenerator.cpp b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
--- a/llvm/tools/llvm-profgen/ProfileGenerator.cpp
+++ b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
@@ -183,6 +183,7 @@
   for (auto Item : Ranges) {
     uint64_t Begin = Item.first.first;
     uint64_t End = Item.first.second;
+    assert(Begin <= End && "invalid instruction range");
     uint64_t Count = Item.second;
     if (Boundaries.find(Begin) == Boundaries.end())
       Boundaries[Begin] = BoundaryPoint();
@@ -194,7 +195,7 @@
   }
 
   uint64_t BeginAddress = UINT64_MAX;
-  int Count = 0;
+  uint64_t Count = 0;
   for (auto Item : Boundaries) {
     uint64_t Address = Item.first;
     BoundaryPoint &Point = Item.second;
@@ -208,6 +209,7 @@
       assert((BeginAddress != UINT64_MAX) &&
              "First boundary point cannot be 'end' point");
       DisjointRanges[{BeginAddress, Address}] = Count;
+      assert(Count >= Point.EndCount && "mismatched live ranges");
       Count -= Point.EndCount;
       BeginAddress = Address + 1;
     }