diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -9665,6 +9665,15 @@
             qsort_compar_f compar) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, qsort, base, nmemb, size, compar);
+  // Run the comparator over all array elements to detect any memory issues.
+  for (SIZE_T i = 0; i < nmemb; ++i) {
+    void *p = (void *)((char *)base + i * size);
+    COMMON_INTERCEPTOR_UNPOISON_PARAM(2);
+    // Compare each element with itself to trigger an equality check, which
+    // typically requires the comparator to look as many of the object fields as
+    // possible.
+    compar(p, p);
+  }
   qsort_compar_f old_compar = qsort_compar;
   qsort_compar = compar;
   SIZE_T old_size = qsort_size;
@@ -9694,6 +9703,15 @@
             qsort_r_compar_f compar, void *arg) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, qsort_r, base, nmemb, size, compar, arg);
+  // Run the comparator over all array elements to detect any memory issues.
+  for (SIZE_T i = 0; i < nmemb; ++i) {
+    void *p = (void *)((char *)base + i * size);
+    COMMON_INTERCEPTOR_UNPOISON_PARAM(3);
+    // Compare each element with itself to trigger an equality check, which
+    // typically requires the comparator to look as many of the object fields as
+    // possible.
+    compar(p, p, arg);
+  }
   qsort_r_compar_f old_compar = qsort_r_compar;
   qsort_r_compar = compar;
   SIZE_T old_size = qsort_r_size;
diff --git a/compiler-rt/test/msan/qsort.cpp b/compiler-rt/test/msan/qsort.cpp
--- a/compiler-rt/test/msan/qsort.cpp
+++ b/compiler-rt/test/msan/qsort.cpp
@@ -1,4 +1,5 @@
 // RUN: %clangxx_msan -O0 -g %s -o %t && %run %t
+// RUN: %clangxx_msan -DPOISON -O0 -g %s -o %t && not %run %t 2>&1 | FileCheck %s
 
 #include <assert.h>
 #include <errno.h>
@@ -65,6 +66,10 @@
   for (int i = 0; i < kSize1; ++i)
     p[i] = i * 2 + (i % 3 - 1) * 3;
   poison_stack_and_param();
+#ifdef POISON
+  __msan_poison(p + 1, sizeof(long));
+  // CHECK: Uninitialized bytes in __msan_check_mem_is_initialized at offset 0 inside [{{.*}}, 8)
+#endif
   qsort(p, kSize1, sizeof(long), compar1);
   __msan_check_mem_is_initialized(p, sizeof(long) * kSize1);
   assert(seen2);