diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1273f28d..34171b0a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Re-add the `ParentLocales` component, this time as a shared component, [#91](https://github.com/ruby-i18n/ruby-cldr/pull/91)
 - Changed the keys and values of `ParentLocales` component to be symbols, [#101](https://github.com/ruby-i18n/ruby-cldr/pull/101)
 - Fixed bug with fallbacks for locales that had more than two segments, [#101](https://github.com/ruby-i18n/ruby-cldr/pull/101)
+- Merge all the related data files before doing lookups, [#98](https://github.com/ruby-i18n/ruby-cldr/pull/98)
 
 ---
 
diff --git a/lib/cldr/export/data.rb b/lib/cldr/export/data.rb
index 67da83c2..e59c8e11 100644
--- a/lib/cldr/export/data.rb
+++ b/lib/cldr/export/data.rb
@@ -51,6 +51,10 @@ def locales
         def components
           self.constants.sort - [:Base, :Export]
         end
+
+        def paths_by_root
+          @paths ||= Dir[File.join(dir, "**", "*.xml")].sort.group_by { |path| Nokogiri::XML(File.read(path)).root.name }
+        end
       end
     end
   end
diff --git a/lib/cldr/export/data/aliases.rb b/lib/cldr/export/data/aliases.rb
index dfa000cb..e9bdf915 100644
--- a/lib/cldr/export/data/aliases.rb
+++ b/lib/cldr/export/data/aliases.rb
@@ -36,11 +36,6 @@ def alias_for(alias_tag)
             ret
           end
         end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/supplemental/supplementalMetadata.xml"
-        end
-
       end
     end
   end
diff --git a/lib/cldr/export/data/base.rb b/lib/cldr/export/data/base.rb
index d3eb3fdd..7c4e01f6 100644
--- a/lib/cldr/export/data/base.rb
+++ b/lib/cldr/export/data/base.rb
@@ -8,6 +8,8 @@ module Data
       class Base < Hash
         attr_reader :locale
 
+        @@doc_cache = {}
+
         def initialize(locale)
           @locale = locale
         end
@@ -53,11 +55,45 @@ def xpath(sources)
           end
 
           def doc
-            @doc ||= Nokogiri::XML(File.read(path))
+            @@doc_cache[paths.hash] ||= merge_paths(paths)
+          end
+
+          def paths
+            @paths ||= begin
+              if locale
+                Dir[File.join(Cldr::Export::Data.dir, "*", "#{Cldr::Export.from_i18n(locale)}.xml")].sort & Cldr::Export::Data.paths_by_root["ldml"]
+              else
+                Cldr::Export::Data.paths_by_root["supplementalData"]
+              end
+            end
           end
 
-          def path
-            @path ||= "#{Cldr::Export::Data.dir}/main/#{Cldr::Export.from_i18n(locale)}.xml"
+          private
+
+          def merge_paths(paths_to_merge)
+            # Some parts (`ldml`, `ldmlBCP47` amd `supplementalData`) of CLDR data require that you merge all the
+            # files with the same root element before doing lookups.
+            # Ref: https://www.unicode.org/reports/tr35/tr35.html#XML_Format
+            #
+            # The return of this method is a merged XML Nokogiri document.
+            # Note that it technically is no longer compliant with the CLDR `ldml.dtd`, since:
+            # * it has repeated elements
+            # * the <identity> elements no longer refer to the filename
+            #
+            # However, this is not an issue, since #select will find all of the matches from each of the repeated elements,
+            # and the <identity> elements are not important to us / make no sense when combined together.
+            return Nokogiri::XML('') if paths_to_merge.empty?
+
+            rest = paths_to_merge[1..paths_to_merge.size - 1]
+            rest.inject(Nokogiri::XML(File.read(paths_to_merge.first))) do |result, path|
+              next_doc = Nokogiri::XML(File.read(path))
+
+              next_doc.root.children.each do |child|
+                result.root.add_child(child)
+              end
+
+              result
+            end
           end
       end
     end
diff --git a/lib/cldr/export/data/country_codes.rb b/lib/cldr/export/data/country_codes.rb
index 9b8c8014..9a78f4bd 100644
--- a/lib/cldr/export/data/country_codes.rb
+++ b/lib/cldr/export/data/country_codes.rb
@@ -9,7 +9,7 @@ def initialize
 
         private
 
-        def country_codes 
+        def country_codes
           doc.xpath("//codeMappings/*").each_with_object({}) do |node, hash|
             if node.name == "territoryCodes"
               type = node.attribute('type').to_s.to_sym
@@ -17,11 +17,7 @@ def country_codes
               hash[type]["numeric"] = node[:numeric] if node[:numeric]
               hash[type]["alpha3"] = node[:alpha3] if node[:alpha3]
             end
-          end        
-        end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/supplemental/supplementalData.xml"
+          end
         end
       end
     end
diff --git a/lib/cldr/export/data/likely_subtags.rb b/lib/cldr/export/data/likely_subtags.rb
index a1c273cc..04b83dd2 100644
--- a/lib/cldr/export/data/likely_subtags.rb
+++ b/lib/cldr/export/data/likely_subtags.rb
@@ -18,11 +18,6 @@ def subtags
             ret
           end
         end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/supplemental/likelySubtags.xml"
-        end
-
       end
     end
   end
diff --git a/lib/cldr/export/data/numbering_systems.rb b/lib/cldr/export/data/numbering_systems.rb
index eef6cf75..6b4de4b1 100644
--- a/lib/cldr/export/data/numbering_systems.rb
+++ b/lib/cldr/export/data/numbering_systems.rb
@@ -30,12 +30,7 @@ def numbering_systems
             ret
           end
         end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/supplemental/numberingSystems.xml"
-        end
-
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/cldr/export/data/rbnf.rb b/lib/cldr/export/data/rbnf.rb
index c82ed92a..c9eab329 100644
--- a/lib/cldr/export/data/rbnf.rb
+++ b/lib/cldr/export/data/rbnf.rb
@@ -11,17 +11,16 @@ def initialize(*args)
         end
 
         def rule_groups
-          if File.exist?(path)
-            select("rbnf/rulesetGrouping").map do |grouping_node|
-              {
-                :type => grouping_node.attribute("type").value,
-                :ruleset => (grouping_node / "ruleset").map do |ruleset_node|
-                  rule_set(ruleset_node)
-                end
-              }
-            end
-          else
-            {}
+          grouping_nodes = select("rbnf/rulesetGrouping")
+          return {} if grouping_nodes.empty?
+
+          grouping_nodes.map do |grouping_node|
+            {
+              :type => grouping_node.attribute("type").value,
+              :ruleset => (grouping_node / "ruleset").map do |ruleset_node|
+                rule_set(ruleset_node)
+              end
+            }
           end
         end
 
@@ -61,11 +60,6 @@ def cast_value(val)
         def fix_rule(rule)
           rule.gsub(/\A'/, '').gsub("←", '<').gsub("→", '>')
         end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/rbnf/#{Cldr::Export.from_i18n(locale)}.xml"
-        end
-
       end
     end
   end
diff --git a/lib/cldr/export/data/rbnf_root.rb b/lib/cldr/export/data/rbnf_root.rb
index 113a4542..9d2b0308 100644
--- a/lib/cldr/export/data/rbnf_root.rb
+++ b/lib/cldr/export/data/rbnf_root.rb
@@ -9,11 +9,11 @@ def initialize
 
         private
 
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/rbnf/root.xml"
+        def paths
+          @paths ||= [File.join(Cldr::Export::Data.dir, "rbnf", "root.xml")]
         end
 
       end
     end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/cldr/export/data/region_currencies.rb b/lib/cldr/export/data/region_currencies.rb
index 0c08db74..51334314 100644
--- a/lib/cldr/export/data/region_currencies.rb
+++ b/lib/cldr/export/data/region_currencies.rb
@@ -34,11 +34,6 @@ def currency(node)
             result
           end
         end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/supplemental/supplementalData.xml"
-        end
-
       end
     end
   end
diff --git a/lib/cldr/export/data/segments_root.rb b/lib/cldr/export/data/segments_root.rb
index 9260217e..4e12aa67 100644
--- a/lib/cldr/export/data/segments_root.rb
+++ b/lib/cldr/export/data/segments_root.rb
@@ -41,8 +41,8 @@ def rules(node)
           end
         end
 
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/segments/root.xml"
+        def paths
+          @paths ||= ["#{Cldr::Export::Data.dir}/segments/root.xml"]
         end
 
         def cast_value(value)
diff --git a/lib/cldr/export/data/subdivisions.rb b/lib/cldr/export/data/subdivisions.rb
index 181e2bf9..05ec3a3a 100644
--- a/lib/cldr/export/data/subdivisions.rb
+++ b/lib/cldr/export/data/subdivisions.rb
@@ -16,19 +16,6 @@ def subdivisions
             result
           end
         end
-
-        def doc
-          begin
-            super
-          rescue Errno::ENOENT
-            @doc = Nokogiri::XML('')
-          end
-        end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/subdivisions/#{Cldr::Export.from_i18n(locale)}.xml"
-        end
-
       end
     end
   end
diff --git a/lib/cldr/export/data/transforms.rb b/lib/cldr/export/data/transforms.rb
index d123132f..2e84fc2f 100644
--- a/lib/cldr/export/data/transforms.rb
+++ b/lib/cldr/export/data/transforms.rb
@@ -66,8 +66,8 @@ def fix_rule(rule)
             gsub("↔", '<>')
         end
 
-        def path
-          transform_file
+        def paths
+          [transform_file]
         end
 
       end
diff --git a/lib/cldr/export/data/variables.rb b/lib/cldr/export/data/variables.rb
index 7a0f30de..65f4eeeb 100644
--- a/lib/cldr/export/data/variables.rb
+++ b/lib/cldr/export/data/variables.rb
@@ -31,11 +31,6 @@ def fix_var_name(var_name)
         def split_value_list(value_list)
           value_list.strip.split(/[\s]+/)
         end
-
-        def path
-          @path ||= "#{Cldr::Export::Data.dir}/supplemental/supplementalMetadata.xml"
-        end
-
       end
     end
   end
diff --git a/test/export/data/base_test.rb b/test/export/data/base_test.rb
new file mode 100644
index 00000000..6d9152a1
--- /dev/null
+++ b/test/export/data/base_test.rb
@@ -0,0 +1,53 @@
+# encoding: utf-8
+
+require File.expand_path(File.join(File.dirname(__FILE__) + '/../../test_helper'))
+
+class TestBase < Test::Unit::TestCase
+  test "#paths finds all the language-dependent data files" do
+    expected = [
+      "annotations/af.xml",
+      "annotationsDerived/af.xml",
+      "casing/af.xml",
+      "collation/af.xml",
+      "main/af.xml",
+      "rbnf/af.xml",
+      "subdivisions/af.xml",
+    ].map {|f| File.join(Cldr::Export::Data.dir, f)}
+    assert_equal expected, Cldr::Export::Data::Base.new('af').send(:paths)
+  end
+
+  test "#paths finds all the supplemental data files" do
+    expected_non_transform_files = [
+      "supplemental/attributeValueValidity.xml",
+      "supplemental/characters.xml",
+      "supplemental/coverageLevels.xml",
+      "supplemental/dayPeriods.xml",
+      "supplemental/genderList.xml",
+      "supplemental/languageGroup.xml",
+      "supplemental/languageInfo.xml",
+      "supplemental/likelySubtags.xml",
+      "supplemental/metaZones.xml",
+      "supplemental/numberingSystems.xml",
+      "supplemental/ordinals.xml",
+      "supplemental/pluralRanges.xml",
+      "supplemental/plurals.xml",
+      "supplemental/rgScope.xml",
+      "supplemental/subdivisions.xml",
+      "supplemental/supplementalData.xml",
+      "supplemental/supplementalMetadata.xml",
+      "supplemental/windowsZones.xml",
+      "validity/currency.xml",
+      "validity/language.xml",
+      "validity/region.xml",
+      "validity/script.xml",
+      "validity/subdivision.xml",
+      "validity/unit.xml",
+      "validity/variant.xml",
+    ].map {|f| File.join(Cldr::Export::Data.dir, f)}
+
+    supplemental_data_paths = Cldr::Export::Data::Base.new(nil).send(:paths)
+
+    assert_equal expected_non_transform_files, supplemental_data_paths.reject {|p| p.include?("transforms/")}
+    assert_not_empty supplemental_data_paths.select {|p| p.include?("transforms/")}
+  end
+end