diff --git a/openmp/libomptarget/DeviceRTL/include/Debug.h b/openmp/libomptarget/DeviceRTL/include/Debug.h
--- a/openmp/libomptarget/DeviceRTL/include/Debug.h
+++ b/openmp/libomptarget/DeviceRTL/include/Debug.h
@@ -17,6 +17,8 @@
 /// {
 extern "C" {
 void __assert_assume(bool cond, const char *exp, const char *file, int line);
+void __assert_fail(const char *assertion, const char *file, unsigned line,
+                   const char *function);
 }
 
 #define ASSERT(e) __assert_assume(e, #e, __FILE__, __LINE__)
diff --git a/openmp/libomptarget/DeviceRTL/src/Debug.cpp b/openmp/libomptarget/DeviceRTL/src/Debug.cpp
--- a/openmp/libomptarget/DeviceRTL/src/Debug.cpp
+++ b/openmp/libomptarget/DeviceRTL/src/Debug.cpp
@@ -26,6 +26,13 @@
 
   __builtin_assume(cond);
 }
+
+void __assert_fail(const char *assertion, const char *file, unsigned line,
+                   const char *function) {
+  PRINTF("%s:%u: %s: Assertion `%s' failed.\n", file, line, function,
+         assertion);
+  __builtin_trap();
+}
 }
 
 #pragma omp end declare target