Index: bolt/include/bolt/Core/MCPlusBuilder.h
===================================================================
--- bolt/include/bolt/Core/MCPlusBuilder.h
+++ bolt/include/bolt/Core/MCPlusBuilder.h
@@ -639,9 +639,12 @@
     return false;
   }
 
-  /// If non-zero, this is used to fill the executable space with instructions
-  /// that will trap. Defaults to 0.
-  virtual unsigned getTrapFillValue() const { return 0; }
+  /// Used to fill the executable space with instructions
+  /// that will trap.
+  virtual StringRef getTrapFillValue() const {
+    llvm_unreachable("not implemented");
+    return StringRef();
+  }
 
   /// Interface and basic functionality of a MCInstMatcher. The idea is to make
   /// it easy to match one or more MCInsts against a tree-like pattern and
Index: bolt/lib/Core/BinaryEmitter.cpp
===================================================================
--- bolt/lib/Core/BinaryEmitter.cpp
+++ bolt/lib/Core/BinaryEmitter.cpp
@@ -376,7 +376,7 @@
   }
 
   if (opts::MarkFuncs)
-    Streamer.emitIntValue(BC.MIB->getTrapFillValue(), 1);
+    Streamer.emitBytes(BC.MIB->getTrapFillValue());
 
   // Emit CFI end
   if (Function.hasCFI())
@@ -420,7 +420,7 @@
     // case, the call site entries in that LSDA have 0 as offset to the landing
     // pad, which the runtime interprets as "no handler". To prevent this,
     // insert some padding.
-    Streamer.emitIntValue(BC.MIB->getTrapFillValue(), 1);
+    Streamer.emitBytes(BC.MIB->getTrapFillValue());
   }
 
   // Track the first emitted instruction with debug info.
Index: bolt/lib/Rewrite/RewriteInstance.cpp
===================================================================
--- bolt/lib/Rewrite/RewriteInstance.cpp
+++ bolt/lib/Rewrite/RewriteInstance.cpp
@@ -5272,8 +5272,10 @@
       if (!BF.getFileOffset() || !BF.isEmitted())
         continue;
       OS.seek(BF.getFileOffset());
-      for (unsigned I = 0; I < BF.getMaxSize(); ++I)
-        OS.write((unsigned char)BC->MIB->getTrapFillValue());
+      StringRef TrapInstr = BC->MIB->getTrapFillValue();
+      unsigned NInstr = BF.getMaxSize() / TrapInstr.size();
+      for (unsigned I = 0; I < NInstr; ++I)
+        OS.write(TrapInstr.data(), TrapInstr.size());
     }
     OS.seek(SavedPos);
   }
Index: bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
===================================================================
--- bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
+++ bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp
@@ -1132,6 +1132,10 @@
     }
   }
 
+  StringRef getTrapFillValue() const override {
+    return StringRef("\0\0\0\0", 4);
+  }
+
   bool createReturn(MCInst &Inst) const override {
     Inst.setOpcode(AArch64::RET);
     Inst.clear();
Index: bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp
===================================================================
--- bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp
+++ bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp
@@ -171,6 +171,10 @@
     return true;
   }
 
+  StringRef getTrapFillValue() const override {
+    return StringRef("\0\0\0\0", 4);
+  }
+
   bool analyzeBranch(InstructionIterator Begin, InstructionIterator End,
                      const MCSymbol *&TBB, const MCSymbol *&FBB,
                      MCInst *&CondBranch,
Index: bolt/lib/Target/X86/X86MCPlusBuilder.cpp
===================================================================
--- bolt/lib/Target/X86/X86MCPlusBuilder.cpp
+++ bolt/lib/Target/X86/X86MCPlusBuilder.cpp
@@ -397,7 +397,7 @@
     }
   }
 
-  unsigned getTrapFillValue() const override { return 0xCC; }
+  StringRef getTrapFillValue() const override { return StringRef("\314", 1); }
 
   struct IndJmpMatcherFrag1 : MCInstMatcher {
     std::unique_ptr<MCInstMatcher> Base;
Index: bolt/test/runtime/mark-funcs.c
===================================================================
--- /dev/null
+++ bolt/test/runtime/mark-funcs.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+
+int dummy() {
+  printf("Dummy called\n");
+  return 0;
+}
+
+int main(int argc, char **argv) {
+  if (dummy() != 0)
+    return 1;
+  printf("Main called\n");
+  return 0;
+}
+// Check that emitting trap value works properly and
+// does not break functions
+// REQUIRES: system-linux
+// RUN: %clangxx -Wl,-q %s -o %t.exe
+// RUN: %t.exe | FileCheck %s
+// CHECK: Dummy called
+// CHECK-NEXT: Main called
+// RUN: llvm-bolt %t.exe -o %t.exe.bolt -lite=false --mark-funcs
+// RUN: %t.exe.bolt | FileCheck %s