diff --git a/compiler-rt/lib/profile/InstrProfilingFile.c b/compiler-rt/lib/profile/InstrProfilingFile.c
--- a/compiler-rt/lib/profile/InstrProfilingFile.c
+++ b/compiler-rt/lib/profile/InstrProfilingFile.c
@@ -490,6 +490,8 @@
    * __llvm_profile_get_size_for_buffer(). */
   const __llvm_profile_data *DataBegin = __llvm_profile_begin_data();
   const __llvm_profile_data *DataEnd = __llvm_profile_end_data();
+  const uint64_t *CountersBegin = __llvm_profile_begin_counters();
+  const uint64_t *CountersEnd = __llvm_profile_end_counters();
   uint64_t DataSize = __llvm_profile_get_data_size(DataBegin, DataEnd);
   const uint64_t CountersOffset = sizeof(__llvm_profile_header) +
       (DataSize * sizeof(__llvm_profile_data));
@@ -542,8 +544,11 @@
   }
 
   /* Update the profile fields based on the current mapping. */
-  __llvm_profile_counter_bias = (intptr_t)Profile -
-      (uintptr_t)__llvm_profile_begin_counters() + CountersOffset;
+  __llvm_profile_counter_bias =
+      (intptr_t)Profile - (uintptr_t)CountersBegin + CountersOffset;
+
+  /* Return the memory allocated for counters to OS. */
+  lprofReleaseMemoryPagesToOS((uintptr_t)CountersBegin, (uintptr_t)CountersEnd);
 }
 
 static void initializeProfileForContinuousMode(void) {
diff --git a/compiler-rt/lib/profile/InstrProfilingPlatformFuchsia.c b/compiler-rt/lib/profile/InstrProfilingPlatformFuchsia.c
--- a/compiler-rt/lib/profile/InstrProfilingPlatformFuchsia.c
+++ b/compiler-rt/lib/profile/InstrProfilingPlatformFuchsia.c
@@ -192,9 +192,11 @@
   lprofWrite("LLVM Profile: {{{dumpfile:%s:%s}}}\n", ProfileSinkName, VmoName);
 
   /* Update the profile fields based on the current mapping. */
-  __llvm_profile_counter_bias = (intptr_t)Mapping -
-                                (uintptr_t)__llvm_profile_begin_counters() +
-                                CountersOffset;
+  __llvm_profile_counter_bias =
+      (intptr_t)Mapping - (uintptr_t)CountersBegin + CountersOffset;
+
+  /* Return the memory allocated for counters to OS. */
+  lprofReleaseMemoryPagesToOS((uintptr_t)CountersBegin, (uintptr_t)CountersEnd);
 }
 
 #endif
diff --git a/compiler-rt/lib/profile/InstrProfilingUtil.h b/compiler-rt/lib/profile/InstrProfilingUtil.h
--- a/compiler-rt/lib/profile/InstrProfilingUtil.h
+++ b/compiler-rt/lib/profile/InstrProfilingUtil.h
@@ -9,6 +9,7 @@
 #ifndef PROFILE_INSTRPROFILINGUTIL_H
 #define PROFILE_INSTRPROFILINGUTIL_H
 
+#include <inttypes.h>
 #include <stddef.h>
 #include <stdio.h>
 
@@ -73,4 +74,14 @@
 /* Restore previously suspended SIGKILL. */
 void lprofRestoreSigKill();
 
+inline size_t lprofRoundUpTo(size_t x, size_t boundary) {
+  return (x + boundary - 1) & ~(boundary - 1);
+}
+
+inline size_t lprofRoundDownTo(size_t x, size_t boundary) {
+  return x & ~(boundary - 1);
+}
+
+int lprofReleaseMemoryPagesToOS(uintptr_t Begin, uintptr_t End);
+
 #endif /* PROFILE_INSTRPROFILINGUTIL_H */
diff --git a/compiler-rt/lib/profile/InstrProfilingUtil.c b/compiler-rt/lib/profile/InstrProfilingUtil.c
--- a/compiler-rt/lib/profile/InstrProfilingUtil.c
+++ b/compiler-rt/lib/profile/InstrProfilingUtil.c
@@ -12,12 +12,13 @@
 #include <windows.h>
 #include "WindowsMMap.h"
 #else
+#include <errno.h>
+#include <fcntl.h>
 #include <sys/file.h>
+#include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
-#include <fcntl.h>
-#include <errno.h>
 #endif
 
 #ifdef COMPILER_RT_HAS_UNAME
@@ -32,6 +33,10 @@
 #include <sys/prctl.h>
 #endif
 
+#if defined(__Fuchsia__)
+#include <zircon/syscalls.h>
+#endif
+
 #include "InstrProfiling.h"
 #include "InstrProfilingUtil.h"
 
@@ -330,3 +335,21 @@
   prctl(PR_SET_PDEATHSIG, SIGKILL);
 #endif
 }
+
+COMPILER_RT_VISIBILITY int lprofReleaseMemoryPagesToOS(uintptr_t Begin,
+                                                       uintptr_t End) {
+  size_t PageSize = getpagesize();
+  uintptr_t BeginAligned = lprofRoundUpTo((uintptr_t)Begin, PageSize);
+  uintptr_t EndAligned = lprofRoundDownTo((uintptr_t)End, PageSize);
+  if (BeginAligned < EndAligned) {
+#if defined(__Fuchsia__)
+    return _zx_vmar_op_range(_zx_vmar_root_self(), ZX_VMAR_OP_DECOMMIT,
+                             (zx_vaddr_t)BeginAligned,
+                             EndAligned - BeginAligned, NULL, 0);
+#else
+    return madvise((void *)BeginAligned, EndAligned - BeginAligned,
+                   MADV_DONTNEED);
+#endif
+  }
+  return 0;
+}
diff --git a/compiler-rt/lib/profile/WindowsMMap.h b/compiler-rt/lib/profile/WindowsMMap.h
--- a/compiler-rt/lib/profile/WindowsMMap.h
+++ b/compiler-rt/lib/profile/WindowsMMap.h
@@ -36,6 +36,14 @@
 #define MS_INVALIDATE   0x0002  /* invalidate all cached data */
 #define MS_SYNC         0x0010  /* msync synchronously */
 
+/*
+ * madvise() flags
+ */
+
+#define MADV_NORMAL     0   /* no special treatment */
+#define MADV_WILLNEED   3   /* expect access in the near future */
+#define MADV_DONTNEED   4   /* do not expect access in the near future */
+
 /*
  * flock() operations
  */
@@ -59,6 +67,8 @@
 
 int msync(void *addr, size_t length, int flags);
 
+int madvise(void *addr, size_t length, int advice);
+
 int flock(int fd, int operation);
 
 #endif /* _WIN32 */
diff --git a/compiler-rt/lib/profile/WindowsMMap.c b/compiler-rt/lib/profile/WindowsMMap.c
--- a/compiler-rt/lib/profile/WindowsMMap.c
+++ b/compiler-rt/lib/profile/WindowsMMap.c
@@ -112,6 +112,18 @@
   return 0;
 }
 
+COMPILER_RT_VISIBILITY
+int madvise(void *addr, size_t length, int advice)
+{
+  if (advice != MADV_DONTNEED)
+    return -1; /* Not supported. */
+
+  if (!VirtualUnlock(addr, length))
+    return -1;
+
+  return 0;
+}
+
 COMPILER_RT_VISIBILITY
 int lock(HANDLE handle, DWORD lockType, BOOL blocking) {
   DWORD flags = lockType;