Index: bolt/lib/Core/BinaryContext.cpp
===================================================================
--- bolt/lib/Core/BinaryContext.cpp
+++ bolt/lib/Core/BinaryContext.cpp
@@ -41,6 +41,7 @@
 #include <iterator>
 #include <numeric>
 #include <unordered_set>
+#include <unistd.h>
 
 using namespace llvm;
 
@@ -1873,12 +1874,14 @@
 BinaryContext::getBaseAddressForMapping(uint64_t MMapAddress,
                                         uint64_t FileOffset) const {
   // Find a segment with a matching file offset.
+  size_t PgSize = getpagesize();
   for (auto &KV : SegmentMapInfo) {
     const SegmentInfo &SegInfo = KV.second;
-    if (alignDown(SegInfo.FileOffset, SegInfo.Alignment) == FileOffset) {
+    if (alignDown(SegInfo.FileOffset, PgSize) == FileOffset) {
       // Use segment's aligned memory offset to calculate the base address.
-      const uint64_t MemOffset = alignDown(SegInfo.Address, SegInfo.Alignment);
-      return MMapAddress - MemOffset;
+      const uint64_t MMapAddressTruncated = alignDown(MMapAddress, PgSize);
+      const uint64_t MemOffset = alignDown(SegInfo.Address, PgSize);
+      return MMapAddressTruncated - MemOffset;
     }
   }