Index: lldb/include/lldb/Utility/RangeMap.h
===================================================================
--- lldb/include/lldb/Utility/RangeMap.h
+++ lldb/include/lldb/Utility/RangeMap.h
@@ -592,13 +592,17 @@
 struct RangeData : public Range<B, S> {
   typedef T DataType;
 
+  B upper_bound;
   DataType data;
 
-  RangeData() : Range<B, S>(), data() {}
+  RangeData() : Range<B, S>(), upper_bound(), data() {}
 
-  RangeData(B base, S size) : Range<B, S>(base, size), data() {}
+  RangeData(B base, S size) : Range<B, S>(base, size), upper_bound(), data() {}
 
-  RangeData(B base, S size, DataType d) : Range<B, S>(base, size), data(d) {}
+  RangeData(B base, S size, DataType d) : Range<B, S>(base, size), upper_bound(), data(d) {}
+
+  RangeData(B base, S size, B ub, DataType d) : Range<B, S>(base, size), upper_bound(ub),
+      data(d) {}
 };
 
 template <typename B, typename S, typename T, unsigned N = 0,
@@ -609,11 +613,11 @@
   typedef RangeData<B, S, T> Entry;
   typedef llvm::SmallVector<Entry, N> Collection;
 
-  RangeDataVector(Compare compare = Compare()) : m_compare(compare) {}
+  RangeDataVector(Compare compare = Compare()) : m_compare(compare), upper_bound_computed(false) {}
 
   ~RangeDataVector() = default;
 
-  void Append(const Entry &entry) { m_entries.push_back(entry); }
+  void Append(const Entry &entry) { m_entries.push_back(entry); upper_bound_computed = false; }
 
   void Sort() {
     if (m_entries.size() > 1)
@@ -627,11 +631,28 @@
                        });
   }
 
+  // We can treat the vector as a flattened BST, augmenting it with upper bounds (max of
+  // range endpoints) for every index allows us to query for intersections in O(log n) time.
+  void ComputeUpperBounds() {
+    ComputeUpperBounds(0, m_entries.size() - 1);
+    upper_bound_computed = true;
+  }
+
+  B ComputeUpperBounds(int lo, int hi) {
+    if (lo > hi) return B();
+
+    int mid = (lo + hi) / 2;
+    auto entry = m_entries[mid];
+
+    entry.upper_bound = std::max(entry.base + entry.size, std::max(ComputeUpperBounds(lo, mid - 1),
+      ComputeUpperBounds(mid + 1, hi)));
+
+    return entry.upper_bound;
+  }
+
 #ifdef ASSERT_RANGEMAP_ARE_SORTED
   bool IsSorted() const {
     typename Collection::const_iterator pos, end, prev;
-    // First we determine if we can combine any of the Entry objects so we
-    // don't end up allocating and making a new collection for no reason
     for (pos = m_entries.begin(), end = m_entries.end(), prev = end; pos != end;
          prev = pos++) {
       if (prev != end && *pos < *prev)
@@ -677,7 +698,7 @@
     }
   }
 
-  void Clear() { m_entries.clear(); }
+  void Clear() { m_entries.clear(); upper_bound_computed = false; }
 
   bool IsEmpty() const { return m_entries.empty(); }
 
@@ -708,22 +729,41 @@
   }
 
   uint32_t FindEntryIndexesThatContain(B addr,
-                                       std::vector<uint32_t> &indexes) const {
+                                       std::vector<uint32_t> &indexes) {
 #ifdef ASSERT_RANGEMAP_ARE_SORTED
     assert(IsSorted());
 #endif
-    // Search the entries until the first entry that has a larger base address
-    // than `addr`. As m_entries is sorted by their base address, all following
-    // entries can't contain `addr` as their base address is already larger.
-    for (const auto &entry : m_entries) {
-      if (entry.Contains(addr))
-        indexes.push_back(entry.data);
-      else if (entry.GetRangeBase() > addr)
-        break;
-    }
+    if (!upper_bound_computed)
+      ComputeUpperBounds();
+
+    FindEntryIndexesThatContain(addr, 0, m_entries.size(), indexes);
+
     return indexes.size();
   }
 
+  void FindEntryIndexesThatContain(B addr, int lo, int hi,
+                                   std::vector<uint32_t> &indexes) {
+    if (lo > hi) return;
+    int mid = (lo + hi) / 2;
+    auto entry = m_entries[mid];
+
+    // addr is greater than the rightmost point of any interval below mid
+    // so there are cannot be any matches.
+    if (addr > entry.upper_bound) return;
+
+    // Recursively search left subtree
+    FindEntryIndexesThatContain(addr, lo, mid - 1, indexes);
+
+    // If addr is smaller than the start of the current interval it
+    // cannot contain it nor can any of its right subtree.
+    if (addr < entry.base) return;
+
+    if (entry.Contains(addr))
+      indexes.push_back(entry.data);
+
+    FindEntryIndexesThatContain(addr, mid + 1, hi, indexes);
+  }
+
   Entry *FindEntryThatContains(B addr) {
     return const_cast<Entry *>(
         static_cast<const RangeDataVector *>(this)->FindEntryThatContains(
@@ -806,6 +846,7 @@
 protected:
   Collection m_entries;
   Compare m_compare;
+  bool upper_bound_computed;
 };
 
 // A simple range  with data class where you get to define the type of