diff --git a/clang/include/clang/Basic/SanitizerSpecialCaseList.h b/clang/include/clang/Basic/SanitizerSpecialCaseList.h
index d024b7dfc2e85..25d518e7128cf 100644
--- a/clang/include/clang/Basic/SanitizerSpecialCaseList.h
+++ b/clang/include/clang/Basic/SanitizerSpecialCaseList.h
@@ -43,13 +43,18 @@ class SanitizerSpecialCaseList : public llvm::SpecialCaseList {
   bool inSection(SanitizerMask Mask, StringRef Prefix, StringRef Query,
                  StringRef Category = StringRef()) const;
 
+  // Query ignorelisted entries if any bit in Mask matches the entry's section.
+  // Return 0 if not found. If found, return the line number (starts with 1).
+  unsigned inSectionBlame(SanitizerMask Mask, StringRef Prefix, StringRef Query,
+                          StringRef Category = StringRef()) const;
+
 protected:
   // Initialize SanitizerSections.
   void createSanitizerSections();
 
   struct SanitizerSection {
     SanitizerSection(SanitizerMask SM, SectionEntries &E)
-        : Mask(SM), Entries(E){};
+        : Mask(SM), Entries(E) {};
 
     SanitizerMask Mask;
     SectionEntries &Entries;
diff --git a/clang/lib/Basic/NoSanitizeList.cpp b/clang/lib/Basic/NoSanitizeList.cpp
index e7e63c1f419e6..811480f914ec5 100644
--- a/clang/lib/Basic/NoSanitizeList.cpp
+++ b/clang/lib/Basic/NoSanitizeList.cpp
@@ -44,6 +44,13 @@ bool NoSanitizeList::containsFunction(SanitizerMask Mask,
 
 bool NoSanitizeList::containsFile(SanitizerMask Mask, StringRef FileName,
                                   StringRef Category) const {
+  unsigned nosanline = SSCL->inSectionBlame(Mask, "src", FileName, Category);
+  unsigned sanline = SSCL->inSectionBlame(Mask, "src", FileName, "sanitize");
+  // If we have two cases such as `src:a.cpp=sanitize` and `src:a.cpp`, the
+  // current entry override the previous entry.
+  if (nosanline > 0 && sanline > 0) {
+    return nosanline > sanline;
+  }
   return SSCL->inSection(Mask, "src", FileName, Category);
 }
 
diff --git a/clang/lib/Basic/SanitizerSpecialCaseList.cpp b/clang/lib/Basic/SanitizerSpecialCaseList.cpp
index 2dbf04c6ede97..7da36f3801453 100644
--- a/clang/lib/Basic/SanitizerSpecialCaseList.cpp
+++ b/clang/lib/Basic/SanitizerSpecialCaseList.cpp
@@ -63,3 +63,19 @@ bool SanitizerSpecialCaseList::inSection(SanitizerMask Mask, StringRef Prefix,
 
   return false;
 }
+
+unsigned SanitizerSpecialCaseList::inSectionBlame(SanitizerMask Mask,
+                                                  StringRef Prefix,
+                                                  StringRef Query,
+                                                  StringRef Category) const {
+  for (auto &S : SanitizerSections) {
+    if (S.Mask & Mask) {
+      unsigned lineNum =
+          SpecialCaseList::inSectionBlame(S.Entries, Prefix, Query, Category);
+      if (lineNum > 0) {
+        return lineNum;
+      }
+    }
+  }
+  return 0;
+}
diff --git a/clang/test/CodeGen/ubsan-src-ignorelist-category.test b/clang/test/CodeGen/ubsan-src-ignorelist-category.test
new file mode 100644
index 0000000000000..e0efd65df8652
--- /dev/null
+++ b/clang/test/CodeGen/ubsan-src-ignorelist-category.test
@@ -0,0 +1,37 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -fsanitize=signed-integer-overflow -fsanitize-ignorelist=%t/src.ignorelist -emit-llvm %t/test1.c -o - | FileCheck %s -check-prefix=CHECK-ALLOWLIST
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -fsanitize=signed-integer-overflow -fsanitize-ignorelist=%t/src.ignorelist -emit-llvm %t/test2.c -o - | FileCheck %s -check-prefix=CHECK-IGNORELIST
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -fsanitize=signed-integer-overflow -fsanitize-ignorelist=%t/src.ignorelist.contradict1 -emit-llvm %t/test1.c -o - | FileCheck %s -check-prefix=CHECK-ALLOWLISTOVERIDE1
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -fsanitize=signed-integer-overflow -fsanitize-ignorelist=%t/src.ignorelist.contradict2 -emit-llvm %t/test1.c -o - | FileCheck %s -check-prefix=CHECK-ALLOWLISTOVERIDE2
+
+
+// Verify ubsan only emits checks for files in the allowlist
+
+//--- src.ignorelist
+src:*
+src:*/test1.c=sanitize
+
+//--- src.ignorelist.contradict1
+src:*
+src:*/test1.c=sanitize
+src:*/test1.c
+
+//--- src.ignorelist.contradict2
+src:*
+src:*/test1.c
+src:*/test1.c=sanitize
+
+//--- test1.c
+int add1(int a, int b) {
+// CHECK-ALLOWLIST: llvm.sadd.with.overflow.i32
+// CHECK-ALLOWLISTOVERIDE1-NOT: llvm.sadd.with.overflow.i32
+// CHECK-ALLOWLISTOVERIDE2: llvm.sadd.with.overflow.i32
+    return a+b;
+}
+
+//--- test2.c
+int add2(int a, int b) {
+// CHECK-IGNORELIST-NOT: llvm.sadd.with.overflow.i32
+    return a+b;
+}
diff --git a/llvm/lib/Support/SpecialCaseList.cpp b/llvm/lib/Support/SpecialCaseList.cpp
index dddf84cbb1ced..926aadb65d493 100644
--- a/llvm/lib/Support/SpecialCaseList.cpp
+++ b/llvm/lib/Support/SpecialCaseList.cpp
@@ -132,18 +132,24 @@ bool SpecialCaseList::createInternal(const MemoryBuffer *MB,
 Expected<SpecialCaseList::Section *>
 SpecialCaseList::addSection(StringRef SectionStr, unsigned LineNo,
                             bool UseGlobs) {
-  Sections.emplace_back();
-  auto &Section = Sections.back();
-  Section.SectionStr = SectionStr;
-
-  if (auto Err = Section.SectionMatcher->insert(SectionStr, LineNo, UseGlobs)) {
+  auto it =
+      std::find_if(Sections.begin(), Sections.end(), [&](const Section &s) {
+        return s.SectionStr == SectionStr;
+      });
+  if (it == Sections.end()) {
+    Sections.emplace_back();
+    auto &sec = Sections.back();
+    sec.SectionStr = SectionStr;
+  }
+  it = std::prev(Sections.end());
+  if (auto Err = it->SectionMatcher->insert(SectionStr, LineNo, UseGlobs)) {
     return createStringError(errc::invalid_argument,
                              "malformed section at line " + Twine(LineNo) +
                                  ": '" + SectionStr +
                                  "': " + toString(std::move(Err)));
   }
 
-  return &Section;
+  return &(*it);
 }
 
 bool SpecialCaseList::parse(const MemoryBuffer *MB, std::string &Error) {
diff --git a/llvm/unittests/Support/SpecialCaseListTest.cpp b/llvm/unittests/Support/SpecialCaseListTest.cpp
index 4289a5e702155..f9185ea7483ca 100644
--- a/llvm/unittests/Support/SpecialCaseListTest.cpp
+++ b/llvm/unittests/Support/SpecialCaseListTest.cpp
@@ -306,4 +306,23 @@ TEST_F(SpecialCaseListTest, Version2) {
   EXPECT_TRUE(SCL->inSection("sect2", "fun", "bar"));
   EXPECT_FALSE(SCL->inSection("sect3", "fun", "bar"));
 }
+
+TEST_F(SpecialCaseListTest, Version3) {
+  std::unique_ptr<SpecialCaseList> SCL = makeSpecialCaseList("[sect1]\n"
+                                                             "fun:foo*\n"
+                                                             "[sect1]\n"
+                                                             "fun:bar*\n"
+                                                             "[sect2]\n"
+                                                             "fun:def\n");
+  EXPECT_TRUE(SCL->inSection("sect1", "fun", "fooz"));
+  EXPECT_TRUE(SCL->inSection("sect1", "fun", "barz"));
+  EXPECT_FALSE(SCL->inSection("sect2", "fun", "fooz"));
+
+  EXPECT_TRUE(SCL->inSection("sect2", "fun", "def"));
+  EXPECT_FALSE(SCL->inSection("sect1", "fun", "def"));
+
+  EXPECT_EQ(2u, SCL->inSectionBlame("sect1", "fun", "fooz"));
+  EXPECT_EQ(4u, SCL->inSectionBlame("sect1", "fun", "barz"));
+  EXPECT_EQ(6u, SCL->inSectionBlame("sect2", "fun", "def"));
+}
 }